Process for producing dried singulated crosslinked cellulose pulp fibers

ABSTRACT

This invention provides a dried singulated crosslinked cellulose pulp fiber product as well as an apparatus and a method for forming singulated, crosslinked, and dried fibers. In accordance with the process, a feed pulp containing a crosslinker is delivered to a jet drier. The jet drier singulates and dries the feed pulp. The singulated and dried fibers are collected from the jet drier. The feed pulp may be further treated with a treatment substance. The jet drier may be maintained at negative pressure. The product fibers may have low knot count, a low fines count, as well improved kink, curl and twist. The apparatus for carrying out the process may include a pretreatment station for supplying the treatment substance, a pulp feed device designed for pulp, a pulp feed device designed for pulp and foam suspensions, and/or a fiber separation station having a vacuum conveyor.

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application is a continuation-in-part of prior copendingapplication Ser. No. 09/998,143 filed Oct. 30, 2001.

FIELD OF THE INVENTION

[0002] The present invention relates to a dried singulated crosslinkedcellulose pulp fiber product as well as a process and apparatus forproducing dried singulated crosslinked cellulose pulp fibers, and moreparticularly, a process and apparatus for producing dried singulatedcrosslinked cellulose pulp fibers including the step of using a jetdrier to dry the pulp.

BACKGROUND OF THE INVENTION

[0003] Dried singulated cellulose pulp fibers are desirable for manyproducts from absorbent personal articles to a reinforcer in concrete.Currently, in the most common process of making singulated fibers, aroll of conventional pulp fibers is hammermilled into singulated fibers.This process is energy and time intensive, requiring many steps andpieces of processing equipment. Each piece of processing equipmentrequires a significant capital expenditure and occupies valuable factoryfloor space. Further, the current hammermilling process often producesfibers with undesirable physical properties, such as low kink, curl, andtwist.

[0004] This dry singulated pulp will also contain knots of fiber,sometimes referred to as nits or nodules. Knots are fiber clumps thatremain strongly adhered to one another as can be seen by placing a smallportion of pulp into a clear beaker of water and stirring the water tomix the fibers. Most of the fiber will mix into the water as singularfibers, however there will be fiber clumps that are readily visible. Thefiber clumps or knots are undesirable by-products of the hammermillingprocess. The amount of knots in a pulp that has been hammermilled can bequantified by using a screening system with acoustical energy used asthe means to classify the fiber into amounts of knots, accepts andfines. It is desirable to have low knots and fines and high acceptswhere the accepts are the singulated fibers.

[0005] Canadian Patent No. 993618 (Estes, 1976) describes a process forproducing a low density fluff pad or batt from individual fibers thathave significant kink and interlocking to provide improved batt strengthand higher bulk. In accordance with the process, wet pulp is separatedinto individual fibers during the drying stage. The process uses fluidjet drying equipment that employs air-jets or steam-jets for separatingthe fibers. The fibers are laid on a perforated screen upon exiting fromthe jet drier. The process of the Canadian patent produces a mat ofinterlocked fibers.

[0006] Crosslinked fibers are conventionally produced by wetting analready dried roll of conventional pulp fibers with a solutioncontaining a crosslinker prior to hammermilling. The hammermilled pulpcontaining a crosslinker is then run through a flash drier and furtherheated in an oven to complete the crosslinking process. This crosslinkedpulp has a knot content that is greater than 15%. It is desirable tohave a lower amount of knots in crosslinked pulp. Also this conventionalprocess is energy intensive and therefore expensive because the pulp isdried before it is rolled, then hammermilled in wet form withcrosslinker, then dried again.

[0007] Flash drier systems have been used to directly dry dewaterednever dried pulp. The use of flash driers to directly dry dewaterednever dried pulp, however, produces a dried pulp with a high amount ofknots. Typical knot amounts for flash drying of never dried pulps are30-40%. Crosslinker containing pulp dried in this manner also results ina knot content similar to or exceeding this level. An overview of acommercial flash drier, the Flakt Flash Drier, and typical flash drierequipment installation is provided by Larsson and Lindstrom, 1996(“Recent Developments in Pulp Drying”, Larson, O; Lindstrom, B, TheWorld of Pulp and Paper Week, 5^(th) International Conference on NewAvailable Techniques, Jun. 4-7, 1996, Stockholm, Sweden).

SUMMARY OF THE INVENTION

[0008] This invention provides a dried singulated crosslinked cellulosepulp fiber product as well as an apparatus and a method for formingsingulated, crosslinked, and dried fibers that have a relatively lowknot content. In accordance with the process, wet pulp containing acrosslinker and air are introduced into a jet drier. The pulp is driedin the jet drier to form singulated pulp fibers. The pulp is removedfrom the jet drier and separated from the air. The process may be usedon several types of feed pulp and on further treated feed pulp. Theproduct formed by the process has advantageous properties such as a lowknot count, a low fines count, as well as improved kink, curl and twist.The apparatus for carrying out the process may include a pretreatmentstation for supplying a treatment substance, a pulp feed device designedonly for pulp, a pulp feed device designed for suspensions of pulp infoam, and/or a fiber separation station having a vacuum conveyor.

[0009] In accordance with the process described above, the wet pulpcontaining a crosslinker treatment substance, may be further treatedwith a treatment substance before drying to reduce the knot content ofthe pulp fibers. The process also includes producing singulated pulpfibers by introducing wet pulp and air into a jet drier through a rotaryairlock. The rotary airlock has vanes and a housing, with the end of thevanes being spaced from the housing by a distance sufficient to preventwet fibers from clogging the airlock. The process includes producingsingulated pulp fibers by withdrawing the fibers from said jet drier inan air stream at a velocity sufficient to prevent the fibers frominterlocking and knotting. The process also includes producingsingulated pulp fibers by withdrawing the pulp fibers from an outletfrom said jet drier under a partial vacuum.

[0010] The pulp product includes singulated, crosslinked and jet driedfibers with a knot count equal to or less than preferably 15%, morepreferably 10%, even more preferably 5%, and most preferably 2%. Theproduct may be further treated with a treatment substance selected fromthe group consisting of a surfactant and a mineral particulate. Theproduct of singulated, crosslinked, and jet dried fibers can beincorporated into concrete, an absorbent article, a plastic product, apaper product, or a filter product.

[0011] The drying system for the processing of pulp into singulated,crosslinked and dried fibers includes a jet drier, a pulp supplystation, an air supply station, an outlet flow conduit and a fiberseparation station. The jet drier has a jet conduit, a manifold for airintake into the jet conduit, a pulp intake for delivery of pulp into thejet conduit, and a fiber outlet for removal of singulated and driedfibers, outlet air and fines from the jet conduit. The pulp supplystation is coupled to the pulp intake for supplying a feed pulp to thepulp intake. The pulp supply station includes a treatment supply sourcefor delivering a treatment substance to the pulp. The air supply stationis coupled to the manifold for delivering air to the manifold. Theoutlet flow conduit is coupled to the fiber outlet for the transport ofthe fibers, outlet air and fines from the jet conduit. The fiberseparation station is coupled to the outlet flow conduit for separatingthe fibers from the outlet air.

[0012] The present invention thus provides a dried singulatedcrosslinked cellulose pulp fiber product as well as an apparatus and amethod that enable forming singulated, crosslinked, and dried fibers.The process may take wet pulp directly from a pulp mill and produce asingulated product from the never-dried pulp by using a drying processthat singulates the pulp directly. This process forms singulatedcrosslinked fibers with greater kink, curl, and individual twist thanhammermilled fibers. A further advantage is the ability of the presentinvention to produce crosslinked fibers having a low fiber interlock,knot and fines content. Other advantages are the further treatments, inaddition to crosslinking, that can be performed on the pulp that aredifficult or impossible to perform on a roll of dried pulp. Treatmentscan be done on the never-dried pulp that reduce the amount of knots,increase production rate, and/or form fibers having desirablecharacteristics.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The foregoing aspects and many of the attendant advantages ofthis invention will become more readily appreciated as the same becomebetter understood by reference to the following detailed description,when taken in conjunction with the accompanying drawings, wherein:

[0014]FIG. 1 is a schematic diagram of a drying system constructed inaccordance with the present invention suitable for carrying out theprocess in the present invention;

[0015]FIG. 2 is a schematic view of the drying system of the presentinvention with a cross section view of a jet drier and a fiberseparation station;

[0016]FIG. 3 is a cross section view of a pulp feed device of thepresent invention;

[0017]FIG. 4 is an enlarged cross section view of the pulp feed devicerotor of the present invention;

[0018]FIG. 5 is a side view of a mechanical mixer and the jet drier ofthe drying system of the present invention;

[0019]FIG. 6 is an exploded view of the mechanical mixer of the presentinvention;

[0020]FIG. 7 is a perspective view of a fiber separation station of thepresent invention;

[0021]FIG. 8 is a bottom perspective view of the fiber separationstation of the present invention;

[0022]FIG. 9 is an enlarged perspective view of the fiber separationstation of the present invention;

[0023]FIG. 10 is a schematic diagram of an absorbent article of thepresent invention;

[0024]FIG. 11 is a schematic diagram of a concrete or plastic product ofthe present invention;

[0025]FIG. 12 is a schematic diagram of a paper or filter product of thepresent invention;

[0026]FIG. 13 is a schematic diagram of the drying system of the presentinvention including a curing station; and

[0027]FIG. 14 is a schematic diagram of the drying system of the presentinvention including a curing oven.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0028] The present invention provides for processes and apparatus forthe drying, treatment, and singulation of pulp into individual fiberswith low interlocked fibers, knots or nodules. As used herein the term“dried” in regards to fibers, is a term of art generally indicating aweight percentage of water between 2% and 10%, but may fall above orbelow this range. As used herein the term “air” is not limited to pureair but may include any gas consistent with the present invention. Asused herein the term “consistency” means the percentage of solidscontent of a liquid and solid mixture. The specific examples set forthbelow are directed to the drying, treatment, and singulation ofcellulose pulp fibers. However, it should be understood that the presentinvention is also suitable for use in processing other types of naturalfibers and/or synthetic fibers.

[0029] The present invention comprises a drying system having a jetdrier designed to dry wet pulp directly from a pulp mill to a singulatedfiber product. Referring to FIG. 1, a drying system 10 constructed inaccordance with the present invention includes a jet drier 20, a pulpsupply station 40, an air supply station 90, a fiber separation station100, and a fiber collection station 160.

[0030] The pulp supply station 40 is coupled in flow communication withthe jet drier 20. The pulp supply station 40 receives supply pulp from apulp supply source 42 and provides a feed pulp to the jet drier 20 via apulp feed conduit 44. The air supply station 90 is coupled in flowcommunication with the jet drier 20. The air supply station 90 receivessupply air from an air supply source 92 and provides feed air via an airfeed conduit 94 to the jet drier 20. The jet drier 20 is coupled in flowcommunication with the fiber separation station 100 via outlet flowconduit 30. The jet drier 20 exhausts outlet air, substantially driedand singulated fibers, and fines to the fiber separation station 100 viaoutlet flow conduit 30. The fiber separation station 100 is coupled inflow communication with the fiber collection station 160. The fiberseparation station 100 separates the outlet air from the fibers, and mayalso separate a portion of the fines from the fibers. The fibers fromthe fiber separation station 100 are delivered to the fiber collectionstation 160.

[0031] In a preferred embodiment, the apparatus also includes a finesremoval station 170 and a noise reduction station 180. The fiberseparation station 100 is coupled in flow communication with the finesremoval station 170 through fines conduit 172. The fiber separationstation 100 provides outlet air and fines to the fines removal station170 via fines conduit 172. The fines removal station 170 removes thefines from the outlet air and recycles the outlet air back to the airsupply station 90 via air conduit 182. The noise reduction station 180is preferably interposed in air conduit 182 to reduce the noise producedby the drying system 10.

[0032] Referring to FIG. 2, the jet drier 20 includes a loop conduit 22,a pulp intake 24, a manifold 26, and a fiber outlet 28. It will beunderstood that, as used herein, the term “jet drier” means any devicewhich accelerates air into the loop conduit 22, enabling thesimultaneous drying and singulation of a substance flowing though theconduit 22. The pulp intake 24 is coupled to the conduit 22 fordelivering feed pulp to the conduit 22. The manifold 26 is coupled tothe jet drier conduit 22 to deliver feed air via air feed conduit 94into the conduit 22 through a series of nozzles which are directed toinduce a flow within the conduit 22. The fiber outlet 28 is coupled tothe conduit 22 to supply an outlet for outlet air, fibers, and finesflow out of conduit 22.

[0033] The conduit 22 is preferably arranged in a closed loop. Theconduit 22 loop can take various shapes such as circular, elongatedrectangular, a “D” shape, square, or other similar shape. Without beingbound by theory, it is believed that when wet fibers enter the conduit22 loop, a centrifugal separation takes place so that wetter/denserfibers are recirculated along the outer edge of the loop whiledrier/less-dense fibers move towards the inner part of the loop. Air anddried product exit from a fiber outlet 28 placed along the inner part ofthe loop. One suitable jet drier 20 for use in the present invention isa Fluid Energy Aljet Model 4 Thermajet, X0870L, manufactured by FluidEnergy Processing & Equipment Company. Alternatively, the jet drierconduit 22 may be in a shape other than a closed loop. For example, theconduit 22 could be straight. In this embodiment, the fibers may berecovered at the end of the conduit 22.

[0034] The drying system 20 further includes an outlet flow conduit 30coupled to the jet drier 20 fiber outlet 28 and associated with thefiber separating station 100. The outlet flow conduit 30 delivers outletair, fibers, and fines flow to the fiber separating station 100. Theoutlet flow conduit may include a first material handling fan 32. Thefirst material handling fan 32 prevents the fibers and fines fromsettling out of the outlet air if the outlet air slows in the conduit30. However, the first material handling fan 32 may not be necessary ifthe velocity of the outlet air maintains the fibers in suspension. Thediameter of the outlet flow conduit will affect the velocity of theoutlet air. It is desirable to prevent the fibers from settling out ofthe outlet air. If fibers settle out of the outlet air, the fibers havean increased tendency to knot or interlock.

[0035] The pulp supply station 40 may include a first dewatering device46. The first dewatering device 46 is connected in flow communicationwith pulp supply 42 and pulp feed conduit 44. The pulp supply source 42delivers supply pulp directly from the fiberline of a pulp mill to thefirst dewatering device 46. The first dewatering device 46 partiallydewaters the supply pulp from pulp supply 42 and delivers feed pulp viapulp feed conduit 44 to jet drier 20. The first dewatering device 46includes, but is not limited to, devices such as a screw press, beltpress, continuous centrifuge, batch centrifuge, double roll press, orother similar device.

[0036] The supply pulp from pulp supply source 42 will typically have ahigh fluid content, having a 0.01-10% consistency, and more typically a3-10% consistency, although consistencies up to 12% to 15% may beemployed. The supply pulp may be bleached pulp, unbleached pulp,mechanical pulp, chemical pulp, a dissolving grade pulp, once dried andreslurried pulp, or any other suitable pulp. In the present invention,much of this fluid may be removed by the first dewatering device 46.Typically, the first dewatering device 46 removes a portion of the fluidfrom the supply pulp and increases the consistency of the feed pulp to10-55%, prior to drying the feed pulp by the jet drier 20. Preferablythe consistency of the feed pulp is 30 to 50%. The partially dewateredfeed pulp is transported to the jet drier 20 via pulp feed conduit 44.

[0037] The supply pulp may be a pressed wet web of pulp having a basisweight of a substantial amount to provide sufficient stiffness to feedthe web into a shredding device. The basis weight may typically be from500 to 1500 gsm. The wet web supply pulp may be fed into a shreddingdevice such as a rapidly rotating set of rolls containing protrudingpins that tear the web into small pieces of pulp, a material handlingfan, or other similar device.

[0038] The pulp feed conduit 44 may be a pipe, hopper, or otherconveyance device. Additionally, the first dewatering device 46 itselfmay serve as a conveyance device. For example, the first dewateringdevice 46 may be a screw press which could be used to simultaneouslydewater and transport the feed pulp to the jet drier 20. One suitablepulp supply station 40 pulp feed conduit 44 for use in the presentinvention is a shaftless screw conveyor designed and manufactured byMartin Sprocket and Gear, Inc., Martin Conveyor Division. The shaftlessscrew conveyor has a shaftless screw which feeds wet pulp at an inclinethat rises up toward the pulp intake 24 of the jet drier 20. Theshaftless screw conveyor has a hopper at the lower end of the conveyorfor placing supply pulp.

[0039] The pulp supply station 40 may include a treatment supply source48 for incorporating a treatment substance into the feed pulp. Thetreatment supply source 48 may be coupled in flow communication to thepulp supply source 42, the pulp feed conduit 44, the first dewateringstation 46, or anywhere along the pulp supply station 40.

[0040] The treatment supply source 48 may deliver the treatmentsubstance with any apparatus known in the art. For instance, treatmentsupply source 48 may deliver the treatment substance with a conduit,spray system, mixing device, or other device or combination of devices.Where the supply pulp is a pressed wet web of pulp, the treatmentsubstance may be applied to the supply pulp by a spray system, rollercoating system, or a combination of spray system and roller coatingsystem.

[0041] Many treatment substances that may be applied to the feed pulpprior to being dried and singulated by the jet drier 20, are incapableof being incorporated into the traditional process of producing driedsingulated fibers. The traditional process is limited in its ability totreat the fibers since they are in a web form. In this web form,treatment of the fibers must be done by running the web through a bathor spraying the web. The present invention is not limited in this way,since treatment substances may be directly delivered to the pulp. Forexample, the fibers of the supply pulp in the present invention may besuspended within a foam prior to drying by the jet drier 20 or viscoussolutions may be mixed with the supply pulp. Neither one of thesetreatment choices would be practical with the traditional bath treatmentstep. The application of treatment substances that are viscous solutionscannot be accomplished with a traditional pulp machine. Additionally,the harsh conditions of hammermilling limit the practicality of thefibers retaining certain compounds that may be used as treatmentsubstances. For example, coating the fibers with mineral particulate,such as clay, would result in low clay retention with hammermilling, butin the present invention retention may be significantly higher due tothe singulation being accomplished by air rather than mechanical means.Further, the amount of surfactant used to treat pulp on a traditionalpulp machine is limited due to the adverse affect on operations,however, there is no such limitation with the present invention. Intraditional pulp machines, the surfactant decreases the strength of thepulp web. If enough strength is lost, the pulp web will break undernormal tension encountered on a traditional pulp machine.

[0042] The treatment substance delivered by treatment supply source 48may include, but is not limited to, surfactants, crosslinkers,hydrophobic materials, mineral particulates, superplasticizer, waterreducing agents, foams, other materials for specific end-use fiberproperties, and combinations of treatment substances. The termsurfactant includes, but is not limited to oil in water emulsions;surfactants disclosed in U.S. application Ser. No. 08/509,401 to Graefet al.; U.S. Pat. No. 3,554,863 to Hervey et al.; U.S. Pat. No.6,074,524 to Wu et al.; U.S. Pat. No. 6,159,335 to Owens et al.; andCanadian Pat. No. 947915 to Angel et al.; all of which are expresslyincorporated herein by reference. Surfactants impart desirableproperties to pulp fibers such as reducing fiber to fiber bonding,improving absorbency or reducing friction of finished webs. Surfactantsare used in tissue and towel manufacturing, and are used extensively inthe textile industry for numerous enhancements. The classes ofsurfactants include anionic, cationic, nonionic, orampholytic/zwitterionic surface active materials. Examples of anionicsurfactants include sodium stearate, sodium oleate, sodium dodecylsulfate, sodium dodecyl benzene sulfonate, polyether sulfate, phosphate,polyether ester and sulfosuccinate. Examples of cationic surfactantsinclude dodecylamine hydrochloride, hexadecyltrimethyl ammonium bromide,cetyltrimethyl-ammonium bromide, and cetylpyridinium bromide. One classof surfactant is cationic surfactants based on quaternary ammoniumcompounds containing fatty type groups. Examples of non-ionicsurfactants include polyethylene oxides, sorbitan esters,polyoxyethylene sorbitan esters, and alkylaryl polyether alcohols. Anexample of ampholytic or zwitterionic surfactant is dodecyl betaine.Examples of commercial surfactant are EKA Chemicals Inc. Berolcell 587Kwhich is a cationic surface active agent and Process Chemicals, LLCSoftener CWW which is a cationic surfactant used as a yam lubricant.

[0043] The term crosslinker includes, but is not limited to, any one ofa number of crosslinking agents and crosslinking catalysts. Thefollowing is a representative list of useful crosslinking agents andcatalysts. Each of the patents noted below is expressly incorporatedherein by reference in its entirety.

[0044] Suitable urea-based crosslinking agents include substituted ureassuch as methylolated ureas, methylolated cyclic ureas, methylolatedlower alkyl cyclic ureas, methylolated dihydroxy cyclic ureas, dihydroxycyclic ureas, and lower alkyl substituted cyclic ureas. Specificurea-based crosslinking agents include dimethyldihydroxy urea (DMDHU,1,3-dimethyl-4,5-dihydroxy-2-imidazolidinone),dimethyloldihydroxyethylene urea (DMDHEU,1,3-dihydroxymethyl-4,5-dihydroxy-2-imidazolidinone), dimethylol urea(DMU, bis[N-hydroxymethyl]urea), dihydroxyethylene urea (DHEU,4,5-dihydroxy-2-imidazolidinone), dimethylolethylene urea (DMEU,1,3-dihydroxymethyl-2-imidazolidinone), and dimethyldihydroxyethyleneurea (DDI, 4,5-dihydroxy-1,3-dimethyl-2-imidazolidinone).

[0045] Suitable crosslinking agents include dialdehydes such as C₂-C₈dialdehydes (e.g., glyoxal), C₂-C₈ dialdehyde acid analogs having atleast one aldehyde group, and oligomers of these aldehyde and dialdehydeacid analogs, as described in U.S. Pat. Nos. 4,822,453; 4,888,093;4,889,595; 4,889,596; 4,889,597; and 4,898,642. Other suitabledialdehyde crosslinking agents include those described in U.S. Pat. Nos.4,853,086; 4,900,324; and 5,843,061.

[0046] Other suitable crosslinking agents include aldehyde andurea-based formaldehyde addition products. See, for example, U.S. Pat.Nos. 3,224,926; 3,241,533; 3,932,209; 4,035,147; 3,756,913; 4,689,118;4,822,453; 3,440,135; 4,935,022; 3,819,470; and 3,658,613.

[0047] Suitable crosslinking agents include glyoxal adducts of ureas,for example, U.S. Pat. No. 4,968,774, and glyoxal/cyclic urea adducts asdescribed in U.S. Pat. Nos. 4,285,690; 4,332,586; 4,396,391; 4,455,416;and 4,505,712.

[0048] Other suitable crosslinking agents include carboxylic acidcrosslinking agents such as polycarboxylic acids. Polycarboxylic acidcrosslinking agents (e.g., citric acid, propane tricarboxylic acid, andbutane tetracarboxylic acid) and catalysts are described in U.S. Pat.Nos. 3,526,048; 4,820,307; 4,936,865; 4,975,209; and 5,221,285. The useof C₂-C₉ polycarboxylic acids that contain at least three carboxylgroups (e.g., citric acid and oxydisuccinic acid) as crosslinking agentsis described in U.S. Pat. Nos. 5,137,537; 5,183,707; 5,190,563;5,562,740, and 5,873,979.

[0049] Polymeric polyearboxylic acids are also suitable crosslinkingagents. Suitable polymeric polycarboxylic acid crosslinking agents aredescribed in U.S. Pat. Nos. 4,391,878; 4,420,368; 4,431,481; 5,049,235;5,160,789; 5,442,899; 5,698,074; 5,496,476; 5,496,477; 5,728,771;5,705,475; and 5,981,739. Polyacrylic acid and related copolymers ascrosslinking agents are described U.S. Pat. Nos. 5,549,791 and5,998,511. Polymaleic acid crosslinking agents are described in U.S.Pat. No. 5,998,511.

[0050] Specific suitable polycarboxylic acid crosslinking agents includecitric acid, tartaric acid, malic acid, succinic acid, glutaric acid,citraconic acid, itaconic acid, tartrate monosuccinic acid, maleic acid,polyacrylic acid, polymethacrylic acid, polymaleic acid,polymethylvinylether-co-maleate copolymer,polymethylvinylether-co-itaconate copolymer, copolymers of acrylic acid,and copolymers of maleic acid.

[0051] Other suitable crosslinking agents are described in U.S. Pat.Nos. 5,225,047; 5,366,591; 5,556,976; 5,536,369, 6,300,259, and U.S.application Ser. No. 08/509,401 to Graef et al.

[0052] Suitable catalysts can include acidic salts, such as ammoniumchloride, ammonium sulfate, aluminum chloride, magnesium chloride,magnesium nitrate, and alkali metal salts of phosphorous-containingacids. In one embodiment, the crosslinking catalyst is sodiumhypophosphite. Mixtures or blends of crosslinking agents and catalystscan also be used.

[0053] The crosslinking agent is applied to the cellulosic fibers in anamount sufficient to effect intrafiber crosslinking. The amountpreferably applied to the cellulosic fibers can be from about 0.1 toabout 10 percent by weight based on the total weight of fibers. Higherconcentrations can be employed but may not be practical in a productionenvironment. In one embodiment, crosslinking agent is applied in anamount from about 4 to about 6 percent by weight based on the totalweight of fibers.

[0054] The term hydrophobic material includes, but is not limited to,latex, sizing agents used to treat pulp such as alkyl ketene dimer oralkenyl succinic anhydride, rosins and synthetic rosins, waxes, oils, orother chemicals that react with the fiber and render the surfacehydrophobic. The term mineral particulate includes, but is not limitedto, clay, calcined clay, calcium carbonate, calcium sulfate, zinc oxide,talc, titanium dioxide, silicas, fly ash, sodium aluminosilicates, orother minerals. The term superplasticizer includes, but is not limitedto, polymers that contain sulfonic acid groups, modifiedlignosulfonates, sulfonated melamine-formaldehyde condensates,sulfonated naphthalene-formaldehyde condensates, and polycarboxylatederivatives. An example of a commercial superplasticizers include BoralMaterials Technology Boral SP, a sulfonated naphthalene-formaldehydecondensate. The term foam includes, but is not limited to, foamingagents, foamed material, and foams disclosed in U.S. application Ser.No. 09/569,380 to Graef et al., which are expressly incorporated hereinby reference. The term water reducing agent includes, but is not limitedto, water soluble adhesives and plasticizers. An example of a commercialwater reducing agent is methyl cellulose.

[0055] The treatment supply source 48 may also deliver more than onetreatment substance, and may deliver treatment substances in any numberof steps or stages. For instance, the treatment substance may includebinder molecules and particles, where the binder molecules are firstapplied to the fibers and then the particles are added to the bindermolecule coated fibers thus binding the particles to the fibers (asdisclosed in U.S. Pat. No. 5,641,561 to Hansen et al., which isexpressly incorporated herein by reference). Other fiber treatmentsubstances and methods known in the art may be used without departingfrom the present invention.

[0056] In addition to the embodiment described above, the pulp supplystation 40 may be adapted so that the water contained in the pulp supplysource 42 is exchanged for a solvent treatment substance. The termsolvent includes, but is not limited to, alcohols, ketones, ethers,alkanes, aromatics, aldehydes, or other classes of organic materials.The solvent used may be recovered at the fiber separation station 100

[0057] Additional treatment substances may be added to cause an in situprecipitation. When in situ precipitation is desirable, a first mineraltreatment substance is added to the pulp, then a second treatmentsubstance is added to the pulp. The first and second treatmentsubstances react to form a precipitate treatment substance. For example,dissolved calcium hydroxide may be used as the first treatment substanceand dissolved sodium bicarbonate may be used as the second treatmentsubstance. The calcium hydroxide and sodium bicarbonate react toprecipitate calcium carbonate. Other precipitate treatment substancesmay be formed for treating the pulp including, but is not limited to,calcium aluminum silicates, calcium aluminum carbonates, calciumaluminum phosphates, or other mineral precipitates.

[0058] The pulp supply station 40 may include a second dewatering device50. The second dewatering device 50 is inserted in pulp feed conduit 44to be in flow communication with the first dewatering device 46. Thesecond dewatering device 50 may include, but is not limited to, devicessuch as a screw press, belt press, continuous centrifuge, batchcentrifuge, double roll press, or other similar device. Like the firstdewatering device 46, the second dewatering device 50 removes a portionof the fluid so the feed pulp has a consistency of 10-55%, preferably30-50%, prior to drying the feed pulp by the jet drier 20. The partiallydewatered feed pulp is then transported to the jet drier 20 by pulp feedconduit 44. Alternatively, the second dewatering device 50 itself mayserve as a conveyance device. For example, a screw press could be usedto simultaneously dewater and transport the feed pulp to the jet drier20.

[0059] The second dewatering device 50 further dewaters the treated feedpulp, potentially removing a portion of the treatment substance from thepulp. To recover a portion of the separated treatment substance, atreatment recycle conduit 52 may be connected in flow communicationbetween the second dewatering device 50 first dewatering device 46and/or the treatment supply source 48. The incorporation of treatmentsubstance with the pulp may be accomplished through the agitationsupplied by the first and/or second dewatering devices 46 and 50.

[0060] Alternatively, the pulp supply station 40 may include a holdingtank device 54. The holding tank device 54 may be inserted in recycleconduit 52 to be in flow communication with the second dewatering device50. The holding tank device 54 acts as a reservoir to store separatedtreatment substance from the second dewatering device 50 and dispersethe stored separated treatment substance to the first dewatering device46 and/or to the treatment supply source 48.

[0061] The pulp supply station 40 may include a second material handlingfan 56 inserted in flow communication into pulp feed conduit 44. Afterdewatering, the feed pulp may be run through the second materialhandling fan 56 to break apart the larger pieces of feed pulp intosubstantially uniform pieces, prior to introduction into the jet drier20. The second material handling fan 56 may be any de-flaking device,including but not limited to, a buster fan, a pin fluffer, a materialhandling fan, or a shredder.

[0062] The pulp supply station 40 further includes a pulp feed device 60coupled in flow communication with pulp feed conduit 44 and jet drier 20pulp intake 24. The pulp feed device 60 is a wet pulp delivery apparatusthat can produce a regulated continuously consistent supply of feed pulpat a desired feed rate to the pulp intake 24 of the jet drier 20. Thefeed pulp has been previously dewatered and in some cases treated. Thefeed rate of feed pulp is a process variable that has a direct affect onprocess air temperature, process air pressure, end product fiberappearance, and end product fiber knot count. The pulp feed device 60 isa device that separates atmospheric air from an environment of a higheror lower pressure inside the jet drier 20, and/or separates ambienttemperatures from an environment of higher temperatures inside the jetdrier 20. The pulp feed device 60 allows a continuous input of feed pulpto pass through to the jet drier 20 with a minimum flow of atmosphericair entering the jet drier 20. It is an air-lock positive displacementdevice.

[0063] Referring to FIG. 3, the pulp feed device 60 may be a rotary airlock 62 having a rotor 64 with rotor vanes 66 rotatably mounted within arotor housing 68. One suitable rotary air lock 62 for use in the presentinvention is a modified stainless steel Prater Industries Rotary AirLock Feeder model number PAV-6C having a rotor housing, and aCLSD,SS,PAV-6 rotor with six rotor vanes. Referring to FIG. 4, thePrater Industries rotor vanes were supplied from the manufacturer withan end 69 that had standard clearance between the end of each vane andthe rotor housing 68 of less than 0.010 inches. This standard clearancecauses the feed pulp to jam between the rotor vanes 66 and the housing68. Therefore the Rotary Air Lock Feeder was modified to provide aleading edge 69A that would shear the pulp, and an end profile thatwould prevent the pulp between the end 69 and the housing 68 fromrolling into intertwined bundles. The profile of end 69 can be eitherflat or beveled rearwardly and radially inwardly. This modificationallows the feed pulp to run through the pulp feed device 60 withoutdamaging fibers or jamming the pulp feed device 60 and minimizing airleakage. It was found that a 0.030 inch clearance between the leadingedge of each vane 66 and the rotor housing 68 and a 0.050 inch clearanceat the radial centerline of each vane 66 minimized jamming, rolling orair leakage around the rotor 64. A clearance between the rotor and thehousing from 0.010 to 0.050 inches should be effective for minimizingrotor jamming, rolling and air leakage around the rotor 64.

[0064] Referring to FIGS. 2, 5, and 6, a foam feeder 70 may be used inplace of the pulp feed device 60. The foam feeder 70 produces aregulated continuously consistent supply of foamed feed pulp at adesired feed rate to the pulp intake 24 of the jet drier 20. The foamfeeder 70 mixes a surfactant and air with pulp and directly injects afoamed pulp mixture into the jet drier 20. The foam feeder 70 is amechanical mixer that takes pulp feed, adds a surfactant treatmentsubstance and air to the pulp, and mechanically agitates the surfactantto suspend the pulp fibers in a foam medium. The foam feeder 70 includesa mechanical mixer main body 71, a pulp injection port 72, a surfactantinjection port 73, an air injection port 74, and a foam outlet conduit75. The mechanical mixer main body 71 may be any suitable mechanicalmixer known in the art. The pulp injection port 72 is in flowcommunication between the pulp feed conduit 44 and the mechanical mixermain body 71. The pulp injection port 72 supplies pulp feed to themechanical mixer main body 71. The surfactant injection port 73 is inflow communication between the treatment supply source 48 and themechanical mixer main body 71, and is placed in close proximity with thepulp injection port 72. The surfactant injection port 73 suppliessurfactant treatment substance to the mechanical mixer main body 71. Theair injection port 74 is in flow communication between a pressurized airsource 79 and the mechanical mixer main body 71, and is placed in closeproximity with the surfactant injection port 73. The air injection port74 supplies supply air to the mechanical mixer main body 71. The foamoutlet conduit 75 is in flow communication between the mechanical mixermain body 71 and the jet drier 20 pulp intake 24. The foam outletconduit 75 discharges the pulp fibers suspended in foam from themechanical mixer main body 71 and delivers them to the jet drier 20 pulpintake 24. To optimize the flow of the pulp fibers suspended in foamfrom foam outlet conduit 75, the foam outlet conduit 75 diameter,conduit shape, outlet shape, length inserted into the jet drier 20,and/or angle of insertion into the jet drier 20 may be adjusted. Thefoam feeder 70 may be a screw pump, or any other suitable device knownin the art.

[0065] Alternatively, a pulp feed device 65 may feed pulp to the foamfeeder 70 pulp injection port 72. The pulp feed device 65 may be usedwhere the foam feeder 70 cannot itself produce a regulated continuouslyconsistent supply of feed pulp to the jet drier 20. The pulp feed device65 may be a positive displacement pump, or any other suitable deviceknown in the art.

[0066] The foam outlet conduit 75 may be sealed to the jet drier 20 pulpintake 24 by a pulp intake seal 76. The pulp intake seal 76 may besupplied with an air leak conduit 77 connected to the pulp intake seal76 and running from the jet conduit 22 to ambient air. The air leakconduit 77 provides a limited path between the jet conduit 22 andambient air. The conduit may be supplied with a conventional air valvefor adjusting the leakage amount. Without being bound in theory, it isbelieved that the air leak conduit 77 provides a limited pressure reliefto the jet conduit 22 and prevents unstable operating conditions withinthe jet conduit 22.

[0067] Optionally, the foam feeder 70 includes a treatment injectionport 78 in flow communication between the treatment supply source 48 andthe mechanical mixer main body 71. The treatment injection port 78 maysupply an additional treatment substance to the mechanical mixer mainbody 71. The treatment injection port 78 may be located any where alongthe mechanical mixer main body 71.

[0068] Referring to FIG. 6, one suitable foam feeder 70 for use in thepresent invention is a redesigned and modified mechanical mixer from E.T. Oakes Corporation (Oakes Mixer) for generating a foam suspension ofpulp that can be fed into the jet drier. The foam feeder 70 includes afront stator 80, a rear stator 82, a foaming rotor 84, and a drive shaft86 driven by a motor 87 (shown in FIG. 5). The front stator 80 isconnected about the pulp injection port 72 and defines a circular planeabout the pulp injection port 72. The front stator 80 has multiplecircular rows of teeth 81 extending perpendicularly from the circularplane of front stator 80. These multiple circular rows of teeth 81 arespaced apart, the spaces forming channels between the rows of teeth 81.The rear stator 82 is connected about the foam outlet conduit 75 anddefines a circular plane about the foam outlet conduit 75. The rearstator 82 has multiple circular rows of teeth 83 extendingperpendicularly from the circular plane of rear stator 82. Thesemultiple circular rows of teeth 83 are spaced apart, the spaces formingchannels between the rows of teeth 83. The foaming rotor 84 defines acircular plane and has multiple circular rows of teeth 85 extendingperpendicularly from both sides of the foaming rotor 84. One set of thefoaming rotor 84 circular rows of teeth 85 fit within the channelsformed by the front stator 80 circular rows of teeth 81. Likewise theother set of the foaming rotor 84 circular rows of teeth 85 fit withinthe channels formed by the rear stator 82 rows of teeth 83. This allowsthe foaming rotor 84 to be rotatably associated with both the front andrear stators 80 and 82. The front and rear stators 80 and 82 areconnected together about foaming rotor 84, and the foaming rotor 84 isrotatably associated with both the front and rear stators 80 and 82. Thedrive shaft 86 is connected to the center of the foaming rotor 84 andruns from the foaming rotor 84, through the foam conduit 75, and tomotor 87 (shown in FIG. 5).

[0069] Referring now to both FIGS. 5 and 6, As pulp feed is forced fromthe pulp injection port 72 into front stator 80, the pulp feed contactsthe stationary teeth 81 of front stator 80 and the rotating teeth 85 offoaming rotor 84. The pulp is forced out from the pulp injection port 72along the surface of the front stator 80, around the rotating foamingrotor 84, along the surface of the rear stator 82, and out the foamoutlet conduit 75. While the pulp is in contact with the front stator80, the surfactant treatment substance is forced from the surfactantinjection port 73 into contact with the pulp feed front stator teeth 81and the foaming rotor teeth 85. The supply air is also forced from theair injection port 74 into contact with the pulp feed, front statorteeth 81, and the foaming rotor teeth 85. The foaming rotor 84 mixes thepulp feed, surfactant and air together. The mechanical agitation of thefoaming rotor 84 causes the pulp feed fibers to be suspended in a foam.The foamed pulp feed may then be fed directly into the jet drier 20 viathe foam outlet conduit 75. The consistency of the foamed feed pulp maybe 30% or less.

[0070] Referring to FIG. 6, optionally, drive shaft 86 is connected tothe center of the foaming rotor 84 by an auger head 88. The auger head88 has a generally conical shape, and may have a protrusion 89 from theface of the conical surface of auger head 88. The auger head 88 servesto force the pulp feed from pulp injection port 72 toward the rotatingteeth 85 of foaming rotor 84. The protrusion 89 serves to break up thepulp feed and enhance mixing of the pulp feed with the surfactanttreatment substance.

[0071] The Oakes mixer was modified by placing the foam outlet conduit75 at the original inlet of the Oakes mixer. Without being bound intheory, it has been found that superior mixing is achieved when the pulpinjection port 72 has a greater diameter than foam outlet conduit 75.The original outlet of the Oakes mixer was enlarged to increase flow offeed pulp into pulp injection port 72, and to place the feed pulp incontact with the teeth 85 of rotor 84. The Oakes mixer, originally cameequipped with a nut for connecting the drive shaft 86 to the center ofthe foaming rotor 84; and this was replaced by the auger head 88 above.Additionally, several rows of teeth (81, 83, and 85) were removed fromthe Oakes mixer to improve mixing and increase throughput.

[0072] Referring again to FIG. 2, the air supply station 90 may includean air pump 96 and an air heater 98. The air pump 96 receives supply airvia the air supply source 92 and is coupled in flow communication withair feed conduit 94. The air heater 98 is inserted into air feed conduit94 and in flow communication with air pump 96 and the jet drier 20manifold 26 via air feed conduit 94.

[0073] The air pump 96 may be a positive displacement high volume airpump that delivers the supply air at a positive air pressure and at afixed volume to the air heater 98. One suitable air pump 96 for use inthe present invention is a Roots-Dresser universal rotary lobe blowersystem (model number 45 URAI) with inlet silencer type CCF-4 with apaper element, a discharge silencer type Universal SD-4, filtration andelectric 15 hp drive motor. The flow rate may be 300 SCFM. The deliveredpressure may be 5 PSIG. The pump speed may be 3176 RPM. The drive motormay run at 1800 RPM. The air pump 96 may have a gauge range of 0 to 15psig and it may be fitted with a pressure relief valve set at 6 psig.The air heater 98 heats the supply air and delivers the feed air to themanifold 26 of the jet drier 20. The manifold 26 may feed the feed airtangentially into the jet drier 20 conduit 22 loop for the purpose ofcreating turbulence for fiberizing-and drying the feed pulp inside thejet drier 20.

[0074] The air heater 98 may be a flow through type heater that iscontrolled to regulate the air temperature supplied to the jet driermanifold 26 nozzles that feed the conduit 22. The air heater 98 may bean electric heater, a gas heater or any other form of heater. Onesuitable air heater 98 for use in the present invention is a WatlowElectric Immersion heater, model number 700-96BD2459 that uses 480 VACline voltage, and has a pressure rating of 150 psig at 1,050° F. The airheater 98 over temperature protection uses a type K thermocouple and aWatlow series 92 controller. The air heater 98 process temperatureregulator uses type J thermocouples and Watlow series 965 auto tuningcontroller. The process air temperature is a process variable that has adirect affect on end product fiber appearance, end product fiber knotcount, and fines content.

[0075] Upon exiting the jet drier 20, the outlet air, fibers, and finesmay be transported along the outlet flow conduit 30 to be recovered bythe fiber separation station 100. The fiber separation station 100 maybe a vacuum conveyor 110 slidably associated with outlet flow conduit 30through a head box 140. The vacuum conveyor 110 includes a screen 112, afirst roller 118, a second roller 120, a primary fan vacuum box 122, aprimary fan 128, a secondary fan vacuum box 130, and a secondary fan134.

[0076] The vacuum conveyor 110 screen 112 is a porous conveyor beltdevice which passes the outlet air and fines through the screen 112while preventing the flow of fiber through the screen 112. The screen112 is a continuous loop rotatably coupled to the first roller 118 andthe second roller 120. The screen 112 thus provides a screen upperportion 113 having a screen upper surface 114 and a screen lower surface116, and a screen lower portion 117. The outlet flow conduit 30 from thejet drier 20 is slidably associated with the vacuum conveyor 110 by thehead box 140 so that the outlet flow conduit 30 is in flow communicationwith the upper surface 114 of the screen 112. The outlet flow conduit 30delivers fibers, fines, and outlet air to the upper surface 114. Thescreen 112 passes the outlet air through the upper surface 114 whileretaining fibers on the upper surface 114. A fraction of the fines maybe passed through the screen 112. Alternatively, the screen 112 maycollect the fines by trapping them in the fibers as the fibers areretained under the outlet flow conduit 30 on the moving conveyor screen112. This trapping of fines may result in a level of fines and opacitythat does not require subsequent fines removal at the fines removalstation 170. The rotating screen 112 transports the fibers from theoutlet flow conduit 30 toward the fiber collection station 160, definingan upstream to downstream flow of fibers.

[0077] Referring to FIGS. 7 and 8, the primary fan vacuum box 122 is aplenum that allows passage of outlet air and fines from the outlet flowconduit 30 through the screen to the primary fan 128. Referring to FIG.7, the primary fan vacuum box 122 has an inlet 124 and an outlet 126.The primary fan vacuum box inlet 124 is positioned below the screen 112upper portion 113 and slidably associated with the lower surface 116 ofscreen 112 directly under the head box 140, and is thus in flowcommunication with outlet flow conduit 30 through head box 140 andscreen 112. The inlet to the primary fan vacuum box 122 is matched insize to the head box 140 to allow the head box 140 to seal against theprimary fan vacuum box 122 conduit opening while allowing the screen 112to freely pass therebetween without allowing tramp air to affect thevacuum generated by the primary fan 128.

[0078] Referring to FIG. 2, The vacuum conveyor 110 primary fan 128 iscoupled in flow communication between the primary fan vacuum box outlet126 and fines conduit 172. The primary fan 128 pulls the outlet air fromthe outlet flow conduit 30, through the head box 140, through the screen112 upper surface 114, through the primary fan vacuum box 122, and tothe primary fan 128 for expulsion to fines conduit 172. The primary fanvacuum box 122 allows the primary fan 128 to generate enough vacuum onthe jet drier 20 to transport the fiber from the jet drier 20 to thescreen 112. The porous conveyor screen 112 retains a portion of thefibers from passing through to the primary fan 128. The porous conveyorscreen 112 conveys the fibers away from the outlet flow conduit 30 andtoward the second roller 120, by rotating about the first and secondrollers 118 and 120. The fibers thus form a mat on the screen uppersurface 114.

[0079] The vacuum or negative pressure is defined herein as the null.The null is an internal positive or negative pressure inside the jetdrier 20 that is measured in the centrifugal part of the process airstream near the pulp intake 24 and between the pulp intake 24 and thefiber outlet 28 of jet drier 20. The null is a process control variablethat has a direct affect on the through put of the jet drier 20 and theknot count of the fibers. The main variables that affect null are asfollows: the vacuum generated by the primary fan 128 on the jet drier20, feed rate of the feed pulp into the jet drier 20, moisture contentof the feed pulp, non-uniformity in pulp size and shape, screen 112speed and mesh size, pulp type and treatment, damper settings on theprimary fan 128, and the temperature of process air fed into the jetdrier 20 at the manifold 26. The screen 112 speed is a process controlvariable that has a direct affect on null. The rate at which the screen112 transports the fibers from the outlet flow conduit 30 determines thethickness of the retained fibers being formed on the upper surface 114of screen 112. The thickness of the retained fibers may constrict thevolume of outlet air flowing through the system thus affecting the null.The jet drier 20 null is preferably maintained from 0 to −10 inches ofwater.

[0080] The primary fan 128 may be a side intake, high temperature, highvolume exhaust fan. One suitable primary fan 128 for use in the presentinvention is a steel high temperature side intake material handling fanwith a 10 hp motor with 460 VAC line voltage and may be connected withairtight seals to the primary fan vacuum box 122. An adjustable damperat the exhaust side controls the level of airflow through the primaryfan 128 which has a direct affect on the jet drier 20 null, andtherefore affects the end product fiber appearance and knot count.

[0081] Referring to FIGS. 7 and 8, the secondary fan vacuum box 130 is aplenum that allows the secondary fan 134 to pull air through the screen112 to provide suction on the upper surface 114 of screen 112. Referringto FIG. 7, the secondary fan vacuum box 130 has an inlet 131 and outlet132. The secondary vacuum box inlet 131 is slidably associated with thelower surface 116 of the screen 112 and is positioned below the upperportion 113 of screen 112 downstream from the primary fan vacuum box122. The inlet to the secondary fan vacuum box 130 is positioned justdownstream of the terminus of the head box 140. The secondary vacuum boxoutlet 132 is in flow communication with the secondary fan 134.

[0082] It will be understood that although the vacuum conveyor 110 hasbeen described as having primary and secondary fans 128 and 134, asingle fan device with dampers may serve as both the primary andsecondary fans 128 and 134 without departing from the present invention.The fan vacuum boxes 122 and 130 may have a honeycomb shaped baffle todistribute the intake of fresh air through the mat of fibers on thescreen upper portion 113.

[0083] Referring to FIG. 2, the vacuum conveyor 110 secondary fan 134 iscoupled in flow communication between the secondary fan vacuum boxoutlet 132 and fines conduit 172. The secondary fan 134 provides avacuum which pulls on the retained fibers being conveyed on the uppersurface 114. The secondary fan 134 pulls air through the screen 112,through the secondary fan vacuum box 130, and to the secondary fan 134for expulsion to fines conduit 172. The porous conveyor screen 112prevents the fibers from passing through to the secondary fan 134. Thesecondary fan 134 retains the fibers on the screen 112 while the screen112 is in motion and aids in the extraction and transport of the fibersby creating a vacuum that is strong enough to prevent the primary fan128 from pulling fibers back into the head box 140. Without thesecondary vacuum 134 to hold the fibers in place on the screen 112, thevacuum created by the primary fan 128 in the head box 140 may pull thefibers back into the head box 140. Without the secondary vacuum 134 theresult could be a variable fiber thickness inside the head box 140causing a fluctuation in null resulting in non-uniform deposition offibers, inconsistent fiber separation in the end product, or processshut down because the fibers remain in and plug the head box 140.

[0084] The secondary fan 134 may be a side intake low velocity exhaustfan. One suitable secondary fan 134 for use in the present invention isa fan manufactured by Buffalo with a ¼ hp motor with 110 VAC linevoltage. It has variable speeds and may be connected with airtight sealsto the secondary fan vacuum box 130.

[0085] Referring to FIGS. 7 and 8, the vacuum conveyor 110 includes asupport structure 135. The support structure 135 provides a surface tosupport the moving screen 112. The support structure 135 is shownextending between and supporting the first roller 118 and the secondroller 120, along the same plane as that of the screen lower surface116. The openings of the vacuum boxes are located in the support surface135. It will be understood that, although shown as a single object, thesupport structure 135 may comprise many separate support structuresunassociated with one another.

[0086] The vacuum conveyor 110 may optionally include a screen vacuum137. The screen vacuum 137 removes any residual fibers from the screen112 before the screen 112 receives new fibers from outlet flow conduit30. The screen vacuum 137 may be located anywhere along screen 112 afterthe fiber has been removed. In one embodiment, the screen vacuum 137 isa vacuum manifold slidably associated with the upper surface 114 ofscreen 112, upstream of the head box 140. One suitable screen vacuum 137for use in the present invention is a Sears Shop Vacuum and anunmodified vacuum attachment. Alternatively, the primary fan 128 may beused as the vacuum source for the screen vacuum 137. In anotherembodiment, an air supply device may be positioned on the opposite sideof screen 112 from the screen vacuum 137 to force air through the screen112 and into the screen vacuum 137.

[0087] The vacuum conveyor 110 may optionally include a separationdevice 138. The vacuum conveyor 110 separator device may be a thinphysical barrier running across and slidably associated with the uppersurface 114 of the screen 112 above the downstream end of the secondaryvacuum box 130. The separation device 138 serves to loosen the retainedfibers from the upper surface 114 of the screen 112 so that the fibersmay easily be removed from the screen 112, for instance by gravity, atthe vacuum conveyor 110 terminal end adjacent roller 120. The separatordevice 138 may also separate the fibers from the screen 112 and re-laythem on the screen 112. The fibers may then be collected at the fibercollection station 160 into a bulk mass which can be compressed into abale for shipping to a customer. One suitable separation device 138 foruse in the present invention is a blade made from Teflon sheet 0.030inches thick by 2 inches wide placed at a 45 degree angle across thescreen 112 at the downstream end of the secondary fan vacuum box 130 andsecured at both ends of the separation device 138 to the supportstructure 135.

[0088] Alternatively, the separation device 138 may be a gas blowingdevice operatively associated with the screen 112, and located beneaththe screen 112 downstream from the secondary vacuum box 130. The gasblowing separation device 138 would force gas up through screen 112 toseparate the fibers from the screen.

[0089] The fiber separation station 100 includes a head box 140 coupledto the end of the outlet flow conduit 30, for slidably associatingoutlet flow conduit 30 with screen 112. The head box 140 is an apparatuswhere the separation of entrained fibers and outlet air occurs. In oneembodiment, the head box 140 has a vacuum tight seal against uppersurface 114 of the screen 112 where the outlet air and fines areremoved. The fibers are trapped on the moving screen 112 and the outletair and fines pass through the mat of fiber and through the screen 112.

[0090] Referring to FIG. 9, the head box 140 includes a head box shell142, an out feed roller 145 and a dynamic lip seal 146. The head boxshell 142 is in flow communication between the outlet flow conduit 30and the upper surface 114 of the screen 112. The head box 140 out feedroller 145 is positioned at the downstream end of head box shell 142(also referred to as the outlet side of the head box shell 142). Thehead box 140 out feed roller 145 is rotatably and movably coupled to thehead box shell 142, and rollably associated with the upper surface 114of the screen 112. The dynamic lip seal 146 is positioned above the outfeed roller 145 at the downstream end of box shell 142. The dynamic lipseal 146 is hingedly coupled to the head box shell 142, and slidablyassociated with the out feed roller 145.

[0091] The head box 140 may be composed of a low friction material,wherever moving parts are in contact. For instance, the head box shell142 may be composed of Teflon where the head box shell 142 contacts thescreen 112. Additionally, the head box shell 142 may be composed ofTeflon where the head box shell 142 contacts the out feed roller 145.

[0092] The head box shell 142 preferably includes vertically orientedslots 143. The axles of the out feed roller 145 are positioned in theslots 143. The slots 143 allow the out feed roller 145 to move in an upand down manner to adjust for the varying thickness of the fibers onscreen 112.

[0093] The out feed roller 145 is positioned at the downstream end ofhead box 140 to provide a force for pulling the fibers along the screen112 and out of the head box 140. The out feed roller 145 may otherwisebe a belt or rotor, or other similar device. The out feed roller 145 maybe powered by any conventional source. The bottom surface of the outfeed roller 145 provides an additional force for pulling the fibersalong the screen 112 and out of the outlet flow conduit 30. The out feedroller 145 may be made from Teflon coated steel.

[0094] The dynamic lip seal 146 allows the head box 140 to maintain avacuum tight seal against upper surface 114 of the screen 112. Thedynamic lip seal 146 seals the out feed roller 145 to the head box shell142. This design allows the out feed roller 145 to rotate and travelvertically to compensate for non-uniform fiber thickness at the out feedof the head box 140, without drawing tramp air from around the out feedroller 145. The dynamic lip seal may be made from an inflexible piece147 joined to a flexible piece 149 by a pivot portion 148. The pivotpotion 148 is rotatably coupled to the head box shell 142. Theinflexible piece 147 moves up and down in response to the motion of outfeed roller 145. The flexible piece 149 allows the inflexible portion tomove, while maintaining a vacuum seal against the head box shell 142.The inflexible piece 147 and the flexible piece 149 may be formed ofTeflon having differing thickness.

[0095] Optionally, the head box 140 further may include a pair of drivewheels 150 for driving the out feed roller 145. The drive wheels 150 arerotatably coupled to the upstream end of head box shell 142, in drivingcommunication with the out feed roller 145, and also in mechanicalcommunication with the screen 112. The drive wheels 150 rotate inresponse to the movement of screen 112 and transfer that movement to theout feed roller 145 to rotate the out feed roller 145. The drive wheels150 drive the out feed roller 145 with the use of a coupling device 151.The coupling device 151 may be a chain coupling or any other devicecapable of mechanically associating the drive wheels 150 and out feedroller 145 to turn in unison. It is preferred that the drive wheels 150be coupled to the out feed roller 145 at a 1:1 ratio, to enable thesurface of out feed roller 145 to rotate at the same rate as screen 112.

[0096] The head box 140 may also include a height adjustment structure154. The height adjustment structure 154 is connected to the head boxshell 142 and to the support structure 135. The height adjustmentstructure 154 enables space between the head box shell 142 and screen112 to be adjusted. The height adjustment structure 154 includes a frame155, an adjustment nut 156, and an adjustment bolt 157. The frame 155 isconnected to the head box shell 142. The adjustment bolt 157 isconnected to the support structure 135. The adjustment nut 156 isadjustably connected to the adjustment bolt 157 and is also connected tothe frame 155. As the adjustment nut 156 is adjusted along theadjustment bolt 157, the adjustment nut 156 acts on the frame 155 toincrease or decrease the space between the head box shell 142 and screen112.

[0097] Alternatively the fiber separation station 100 may be a cyclone,bag house, or other similar device for removing fines and fiber togetherfrom outlet air. The fiber separation station 100 may then recycle theseparated outlet air back to the air supply station 90. In thisembodiment, the fines removal station 170 may be located upstream alongconduit 30, to remove the fines from the fibers prior to the fibersbeing recovered at the fiber separation station 100.

[0098] Referring again to FIG. 2, the drying system 10 fines removalstation 170 receives outlet air and fines from the fiber separationstation 100. The fines removal station 170 is coupled in flowcommunication with the fines conduit 172 and the air conduit 182. Thefines removal station receives fines and outlet air from fines conduit172, removes at least a portion of the fines, and discharges the outletair to the air conduit 182. The fines removal station 170 may thenrecycle the outlet air back to the air supply station 90. The finesremoval station 170 may be a cyclone, bag house, or other similardevice.

[0099] Alternatively, the fines removal station 170 is coupled to theoutlet flow conduit 30 between the jet drier 20 and the fiber separationstation 100. The fines removal station 170 in this embodiment mayinclude a cyclone similar to that used as a dust collector for sawdustin wood shops. The fines removal station 170 receives outlet air, fines,and fibers from the jet drier; removes at least a portion of the fines;and sends the fiber coming from the jet drier 20 to the fiber separationstation 100. The fines removal station 170 of this embodiment mayfurther include a second cyclone, bag house, or other similar devicelocated at the primary and secondary fan 128 and 134 outlets. Thissecond cyclone may also receive the filtered fines exhaust from thefirst cyclone.

[0100] The drying system 10 noise reduction station 180 is inserted intoair conduit 182 and in flow communication with the fines removal station170 via air conduit 182. The noise reduction station 180 provides areduction in the noise produced by the drying system 10. The noisereduction station 180 receives outlet air from the fines removal station170 via air conduit 182, absorbs kinetic energy from the outlet air, anddischarges the outlet air via air conduit 182. The discharged outlet airmay be vented to the atmosphere or recycled to the air supply station90.

[0101] Alternatively the noise reduction station 180 is directly coupledto the primary and secondary fans 128 and 134. The noise reductionstation 180 may be a cyclone ducted to the exhaust from the primary fan128. The exhaust from the primary fan 128 is discharged into the inputside of the cyclone and the cyclone outlet ports are independentlyvented to atmosphere. The exhaust from the secondary fan 134 may bevented to the cyclone or to the cyclone outlet ports. Additionally, thefines removal station 170 may also serve as a noise reduction station.

[0102] Referring to FIG. 13, to produce crosslinked fibers, the dryingsystem 10 may optionally include a curing station 310. The curingstation 310 receives fibers from the fiber separation station 100. Thecrosslinker treated fibers are cured in the curing station 310.Optionally, the crosslinker containing fibers are sent directly to thefiber collection station 160 along flow path 158, but only if thecrosslinker is adequately cured in the jet drier 20. However, completecrosslinking in the jet drier may not be achieved in the relativelyshort time in which the fibers conventionally transit through the drier.In one embodiment, the curing station 310 includes a curing oven 320operatively associated with the fiber separation station 100 to receivefibers from the fiber separation station 100. The curing oven 320 iscoupled in flow communication with the fiber collection station 160. Thefibers from the fiber separation station 100 are delivered to the curingoven 320, the curing oven 320 cures the crosslinker treated fibers, andthe cured fibers are sent to the fiber collection station 160.

[0103] Referring to FIG. 14, the curing station 310 alternativelyincludes a flash drier 340 in addition to curing oven 320. The flashdrier 340 is operatively associated with the fiber separation station100, to receive crosslinker treated fibers from the fiber separationstation 100. The flash drier 340 further dries the crosslinker treatedfibers. The curing oven 320 is operatively associated with the flashdrier 340, to receive the further dried fibers from the flash drier 340.The curing oven 320 is also coupled in flow communication with the fibercollection station 160. The fibers from the flash drier 340 aredelivered to the curing oven 320, the curing oven 320 cures the furtherdried fibers, and the cured fibers are sent to the fiber collectionstation 160.

[0104] It will be understood that although the fiber collection station160 and the curing station 310 have been described as being separatedevices, the fiber collection station 160 and the curing station 310 maybe a unitary device. For instance, the vacuum conveyor 110 may beequipped so that the screen 112 passes through a curing oven 320.

[0105] The drying system 10 described above forms singulated and driedfibers. The process takes wet pulp directly from a pulp mill andproduces a singulated product from the never-dried pulp by using adrying process that singulates the pulp directly. This avoids theintermediate steps of the pulp drier, handling of the pulp reels androlls, and hammermilling in a traditional process. The drying system 10produces fibers having a low knot and fines content. These fibers alsohave physical characteristics such as kink, curl, and individual twistthat are more pronounced than 1 fibers processed by hammermilling. Thedrying system 10 may also produce fibers that have been treated with atreatment substance. The treatments that can be performed on the pulpmay be difficult or impossible to perform on a roll of dried pulp.Treatments can be done on the pulp that reduce the amount of knots,increase production rate, and/or form fibers having desirablecharacteristics.

[0106] Where the fibers have been treated with a crosslinker, it ispreferred that the dried, crosslinked, and singulated fibers produced indrying system 10 have a knot count equal to or less than 15%, morepreferably equal to or less than 10%, more preferably equal to or lessthan 5%, and most preferably equal to or less than 2%. Where the fibershave been treated with an additional treatment substance selected fromthe group consisting of surfactant or mineral particulate material, thefibers have a knot count equal to or less than 15%, more preferablyequal to or less than 10%, more preferably equal to or less than 5%, andmost preferably equal to or less than 2%.

[0107] It is preferred that the dried, crosslinked, and singulatedfibers produced in drying system 10 have a fines count equal to or lessthan 21%, more preferably equal to or less than 15%, and most preferablyequal to or less than 13%. Where the crosslinked fibers have beenfurther treated with a treatment substance of surfactant, the fibershave a fines count equal to or less than 21%, preferably equal to orless than 15%, and more preferably equal to or less than 13%. Where thecrosslinked fibers have been further treated with a treatment substanceof mineral particulate, the fibers have a fines count equal to or lessthan 21%.

[0108] It is preferred that the dried, crosslinked, and singulatedfibers produced in drying system 10 have low knot counts, high acceptscounts, and low fines counts. The crosslinked fibers have a knots countequal to or less than 5%, an accepts count equal to or greater than 80%,and a fines count equal to or less than 15%; preferably a knots countequal to or less than 5%, an accepts count equal to or greater than 80%,and a fines count equal to or less than 13%; more preferably a knotscount equal to or less than 5%, an accepts count equal to or greaterthan 85%, and a fines count equal to or less than 15%; and mostpreferably a knots count equal to or less than 2%, an accepts countequal to or greater than 80%, and a fines count equal to or less than15%. Where the crosslinked fibers have been additionally treated with atreatment substance of surfactant, the fibers have a knots count equalto or less than 5%, an accepts count equal to or greater than 80%, and afines count equal to or less than 15%; preferably a knots count equal toor less than 5%, an accepts count equal to or greater than 80%, and afines count equal to or less than 13%; more preferably a knots countequal to or less than 5%, an accepts count equal to or greater than 85%,and a fines count equal to or less than 15%; and most preferably a knotscount equal to or less than 2%, an accepts count equal to or greaterthan 80%, and a fines count equal to or less than 15%. Where thecrosslinked fibers have been additionally treated with a treatmentsubstance of mineral particulate, the fibers have a knots count equal toor less than 2%, an accepts count equal to or greater than 77%, and afines count equal to or less than 21%; and preferably a knots countequal to or less than 1.6%, an accepts count equal to or greater than77%, and a fines count equal to or less than 21%.

[0109] It is preferred that the dried, crosslinked, and singulatedfibers produced in drying system 10 have a density from 15 to 100 kg/m³,more preferably a density from 25 to 70 kg/m³, and most preferably adensity from 30 to 60 kg/m³. These fibers may later be pressed into amore compact form if desired.

[0110] The dried, crosslinked, and singulated fibers produced in dryingsystem 10 may be used in any number of end products including but notlimited to absorbent articles, concrete products, plastic products,filter product, and paper products. Referring to FIG. 10, the absorbentarticle 210 includes a pervious top portion 212, an impervious bottomportion 214, and an absorbent layer 216 located between the pervious topportion 212 and the impervious bottom portion 214. The absorbent layer216 includes singulated and dried fibers 218. It will be understood thatthe term absorbent article, as used herein, includes but is not limitedto diapers, tampons, sanitary napkins, incontinence guards, bandages andmeat and poultry pads.

[0111] Referring to FIG. 11, the concrete product 220 includes aconcrete matrix 226 having singulated and dried fibers 228 incorporatedtherein. It will be understood that the term concrete products, as usedherein, includes but is not limited to cement, concrete, mortars,precast material, high strength cement products, extruded cementproducts, gypsum products, and any other cementitious material. It willbe understood that while FIG. 11 has been illustrated as a concreteproduct 220, FIG. 11 may also show a plastic product 220 including aplastic matrix 226 having singulated and dried fibers 228 incorporatedtherein. It will be understood that the term plastic products, as usedherein, includes but is not limited to plastics and rubbers.

[0112] Referring to FIG. 12, the paper product 230 includes a papersheet 236 having singulated and dried fibers 238 incorporated therein.It will be understood that the term paper products, as used herein,includes but is not limited to paper and paperboard. It will beunderstood that while FIG. 12 has been illustrated as a paper product230, FIG. 12 may also show a filter product 230 having singulated anddried fibers 238 incorporated therein.

EXAMPLES

[0113] In the processing of pulp into dry singulated fibers used in theexamples below, several process conditions were evaluated. The effectsof variations in the jet drier temperature, feed rate, treatmentapplication, types of pulp, feed rate, and pre-drying dewatering methodswere all explored in the Examples below.

[0114] Unless otherwise noted, the apparatus used for the Examples belowis as follows: pulp was dried and singulated into fibers using a FluidEnergy Aljet Model 4 Thermajet, X0870L jet drier. No modifications weremade to the Model 4 Thermajet. The pulp was fed to the jet drier inseveral different apparatuses. For large runs a shaftless screw conveyormanufactured by Martin Sprocket and Gear, Inc., Martin Conveyor Divisionwas used. It had a hopper at the lower end of the conveyor for placingthe wet pulp, and conveyed the wet pulp up an incline that rose uptowards the pulp feed device on the jet drier. For runs of lowquantities of pulp, a Weyerhaeuser designed and manufactured conveyorwith hopper type feeder for feeding wet pulp was used. For feedingfibers suspended in a foam medium a Weyerhaeuser redesigned and modifiedOakes mixer was used to directly inject foamed pulp into the jet drier.

[0115] In Examples 1-9, the feed pulp used was a pressed wet web of pulphaving a basis weight of a substantial amount to provide sufficientstiffness to feed the web into a shredding device. The wet web wasproduced on a pilot papermachine that had a spray system attached to itto allow treatment of the wet web prior to pressing. A basis weight of500 to 1500 gsm was found to work adequately. The web was fed into theshredding device through a rotating and reversible roller nip and into arapidly rotating set of rolls containing protruding pins that tore theweb into small pieces of pulp.

[0116] The feed pulp was delivered to the jet drier using a stainlesssteel Prater Industries Rotary Air Lock Feeder model number PAV-6Chaving a rotor housing, and a CLSD,SS,PAV-6 rotor with six rotor vanes.The refitted rotor was a custom modified six vane closed end rotor thatwas reduced in diameter to give more clearance between the vane androtor housing so wet pulp could be run through the feeder withoutdamaging fibers or jamming the rotor.

[0117] The feed air was delivered to the jet drier with a Roots-Dresseruniversal rotary lobe blower air pump with silencer and filtration. Themodel number was 45 URAI. The flow rate was 300 SCFM. The deliveredpressure was 5 PSIG. The pump speed was 3176 RPM. The drive motor was anelectric Lincoln 15 hp that was running at 1800 RPM. The air pump had aninlet silencer type CCF-4 with a paper element and a discharge silencertype Universal SD-4. The assembly had a gauge range of 0 to 15 psig andit was fitted with a pressure relief valve set at 6 psig.

[0118] The feed air was heated with a Watlow Electric Immersion airheater, model number 700-96BD2459. The air heater used 480 VAC linevoltage, and had a pressure rating of 150 psig at 1,050° F. The overtemperature protection used a type K thermocouple and a Watlow series 92controller. The process temperature regulator used type J thermocouplesand Watlow series 965 auto tuning controller.

[0119] A material handling fan (MHF) was placed in the ducting betweenthe jet drier and the vacuum conveyor. The MHF was used in Examples 1-8,but was not used in Examples 9-24.

[0120] The outlet air, fibers and fines were delivered to a customdesigned vacuum conveyor via a head box sealed to the conveyor screen. ASears Shop Vacuum with an unmodified vacuum attachment was used for thescreen vacuum. The primary fan was a steel high temperature side intakematerial handling fan with airtight seals to the primary fan vacuum box.The primary fan had a 10 hp motor with 460 VAC line voltage. Anadjustable damper at the exhaust side controlled the level of airflowthrough the fan which had a direct effect on the jet drier null, whichcreated a vacuum of −1 to −5 inches of water. The exhaust from theprimary fan discharged into a cyclone that currently serves the purposeof noise reduction. The secondary fan was manufactured by Buffalo andhad a ¼ hp motor with 110 VAC line voltage. The secondary fan hadvariable speeds and was connected with airtight seals to the secondaryfan vacuum box. The secondary fan discharged to the exhaust side of thecyclone. The separation device was made from Teflon sheet 0.030 inchesthick by 2 inches wide placed at a 45 degree angle across the conveyorscreen at the down stream end of the secondary fan vacuum box.

[0121] In the examples below, “sonic knots” were tested by the followingmethod for classifying dry fluffed pulp into three fractions based onscreen mesh size. The first fraction is the knots and is defined as thatmaterial that is captured by a No. 12 mesh screen. The second fractionis the accepts or the singulated fibers and is defined as that materialthat passes through a No. 12 mesh screen but is captured by a No. 60mesh screen. The third fraction is of the fines and is defined as thatmaterial that passes through a No. 12 and through a No. 60 mesh screen.The separation is accomplished by sound waves generated by a speakerthat are imposed upon a pre-weighed sample of fluff pulp placed on a No.5 mesh screen that is near the top of a separation column where thespeaker sits at the very top. After a set period of time, each fractionis removed from the separation column and weighed to obtain the weightfraction of knots, accepts/singulated fiber and fines.

Example 1

[0122] Singulated dried Douglas fir fiber and treated dried Southernpine fiber was produced by making wet rolls of pulp on a pilotpapermachine and hand feeding the wet rolls into the shredding deviceand drier system described above. Some untreated (as is) bleachedSouthern pine and Douglas fir rolls were dried. Additional Southern pinerolls were treated then dried. The treatments on the separate runs ofthe Southern pine feed pulp were as follows: 1. Citric acid; 2. Glyoxal;3. Clay; 4. Hydrophobic latex and fly ash; 5. Hydrophobic latex, fly ashand superplasticizer; 6. Glyoxal, hydrophobic latex, fly ash, andsuperplasticizer; 7. Glyoxal, hydrophobic latex, fly ash, methylcellulose, and superplasticizer; 9. clay; 10. fly ash. The feed rate ofthe pulp was 25-111 g/min OD (oven dried). The solids content wasapproximately 28% in the rolls prior to drying. The outlet temperatureof the drier ranged from 180° C. to 200° C. The inlet temperature wasvaried to attain the outlet temperature. Table 1 summarizes these runsand treatments. The clay and fly ash treated pulp appeared to fiberizethe best. The pulp with methyl cellulose was difficult to run andfiberize. The other runs appeared to fiberize similar to untreated pulp.Sonic knots were not measured on these samples. TABLE 1 Fiber treatment.Citric Acid Glyoxal Feed Cross- Cross- Methyl Super- Outlet Rate LinkerLinker Latex Clay Fly Ash Cellulose plasticizer temp. G/MIN Run # (XLC)(XLG) (L) (CL) (FA) (MC) (SP) (° C.) OD  1 ✓ 200/180 73.9  2 ✓ 200/18063.4  3 ✓ 180 29.6  4 ✓ ✓ 200 113.3  5 ✓ ✓ ✓ 200 69.1  6 ✓ ✓ ✓ ✓ 20098.8  7 ✓ ✓ ✓ ✓ ✓ 200 95.6  8 180 24.8  9 ✓ 200 105.4 10 ✓ 200 81.0  0a200/180 52.5  0b 180 24.8

Example 2

[0123] Unbleached and untreated singulated dried fiber was produced bymaking wet of unbleached Douglas fir (DF) pulp on a pilot papermachineand hand feeding et rolls into the shredding device and drier systemdescribed above. The dried was collected and tested for sonic knotswhich were 5% at one feed rate (in rpm feed roller motor into theshredder) and 15% at a higher feed rate. The outlet rature wasmaintained at 180° C. for both runs. The fines content was about 11% atthe lower feed rate and 12% at the higher feed rate. The accepts were83% at the lower feed rate and 74% at the higher feed rate. Table 2summarizes the data. TABLE 2 Varying feed rate effects on untreated rollsamples. Feed Outlet Knots Rate Temp. Run # Pulp (%) Accepts Fines Speed(° C.) 11 DF 14.73 74.13 11.13 300 180 12 DF 5.07 83.07 11.87 250 180

Example 3

[0124] Bleached and untreated singulated dried fiber samples wereproduced by making wet rolls of bleached Douglas fir pulp on a pilotpapermachine and hand feeding the wet rolls into the shredding deviceand drier system described above. The dried fiber was collected andtested to determine the effect of outlet temperature and feed rate onsonic knots and also the effect on fiber strength as measured by wetzero span tensile strength (ZST). The t86% gives a value to establishthe lower and upper limits of the error range for the ZST results. Therewas no statistically significant change in fiber strength. It was foundthat a higher feed rate produced a higher amount of knots and a higheroutlet temperature produced more knots. Table 3 shows the results. TABLE3 Jet drier runs showing effect of temperature and feed rate on knotsand ZST. ZST Feed Index Ac- Shred- Outlet Rate (Nm/ Knots cepts Finesder Temp. (g OD/ Run # g) t86% (%) (%) (%) Speed (° C.) min) Control 10810.6 13 106 5.7 20.53 66.87 12.60 300 160 70 14 103 1.4 19.87 65.6014.53 300 170 70 15a 105 4.9 25.00 63.67 11.33 300 180 70 15b 101 4.947.33 41.27 11.40 500 180 116 15c 95 2.8 6.40 78.33 15.27 125 180 29 16103 3.5 26.53 60.87 12.60 300 190 70 17 99 4.9 41.93 47.20 10.87 300 20070

Example 4

[0125] Bleached and untreated singulated dried Douglas fir fiber sampleswere produced by slushing wet lap and dewatering it by using acentrifuge and then hand feeding the pulp on a belt conveyor into thedrier system described above. The dried fiber was collected and testedto determine the effect of various wet pulp preparation methods. The wetpulp preparation methods included centrifuged, centrifuged andpin-fluffed, and centrifuged and wetted. Sonics knot levels were testedand the results are shown in Table 4 where it can be concluded that justcentrifuging provides the lowest sonic knots at 14.2%. TABLE 4 Jet drierruns showing effect of pulp preparation on sonic knots. Knots AcceptsFines Inlet Temp. Run # Sample Preparation (%) (%) (%) (° C.) 18Centrifuge & Fluffed 17.9 69.5 12.7 220 19 Centrifuged 14.2 71.4 14.4220 20 Centrifuged & Wetted 16.7 70.7 12.6 220

Example 5

[0126] Fly ash treated and untreated bleached singulated dried Douglasfir fiber samples were produced by slushing wet lap and dewatering it byusing a centrifuge and then hand feeding the pulp on a belt conveyorinto the drier system described above. The fly ash containing pulp wasmade by adding 20% by weight fly ash with high molecular weight anionicretention aid to the slush pulp prior to centrifuging. The dried fiberwas collected and tested to determine the effect of inlet temperatureand fly ash on sonic knots. The results are shown in Table 5 where itcan be seen that fly ash treatment dramatically reduces knots from ahigh of 20% to a low of 1% by weight. Also it can be seen for these runsthat increased inlet temperature and outlet temperature slightly reducedknots. TABLE 5 Singulated Douglas fir pulp with and without fly ash. Ac-Inlet Outlet Sample Fly Ash Knots cepts Fines Temp. Temp. Run #Preparation (%) (%) (%) (%) (° C.) (° C.) 21a Centrifuged, 20.40 66.7312.87 260 160 fluffed 21b Centrifuged 14.13 74.40 11.47 260 180 21cCentrifuged, 16.13 72.93 10.93 300 180 fluffed 22a Centrifuged, FA 20%1.07 80.00 18.93 260 180 fluffed 22b Centrifuged, FA 20% 1.27 79.0019.73 230 180 fluffed

Example 6

[0127] Singulated dried fiber was produced from never dried unbleachedpulp taken from a double roll press in a commercial mill afterdeflaking. The pulp was run as collected from the mill and no treatmentswere done on it. The results are provided in Table 6 which shows thatthe knots ranged from 0.75 to 2.37 percent. Increasing outlettemperature by decreasing feed rate resulted in a slight decrease inknots. Increasing inlet temperature by increasing feed rate increasedknots slightly. Washing, centrifuging and fluffing increased knotsslightly. Re-heating the pulp appeared to have no effect. The “kappa”number is a measure of the amount of lignin remaining in the pulp postpulping, and is quantified by the Tappi Standard Test Methods testnumber T-236. TABLE 6 Untreated centrifuged Douglas fir unbleachedsamples from double roll press. Effect of kappa #, pulp temperature andsample preparation. Inlet Outlet Sample Temp. Temp. Run # PulpPreparation Kappa # Knots Accepts Fines (° C.) (° C.) 23a DF As-is 25 —— — 230 150 23b DF As-is 25 0.90 83.92 15.18 240 150 23c DF As-is 251.36 85.95 12.70 250 155 23d DF As-is 25 1.27 83.60 15.13 260 160 23e DFAs-is 25 1.80 76.33 21.87 300 220 23f DF As-is 25 1.49 80.98 17.53 260160 23g DF As-is 25 1.29 81.04 17.67 260 180 23h DF As-is 25 0.75 84.1015.15 300 180 24a DF As-is 25 1.16 82.41 16.43 260 160 heated pulp 24bDF As-is 25 1.97 81.89 16.13 260 180 heated pulp 25a DF As-is 12 2.3779.21 18.42 260 160 25b DF As-is 12 1.82 82.19 15.99 260 180 25c DFAs-is 12 2.31 80.75 16.95 300 180 26a DF Washed, 25 2.60 82.93 14.47 260160 Centrifuged, fluffed 26b DF Washed, 25 1.87 82.80 15.33 260 180Centrifuged, fluffed

Example 7

[0128] Bleached and untreated singulated dried fiber samples wereproduced by making wet rolls of bleached Douglas fir pulp on a pilotpapermachine and hand feeding the wet rolls into the shredding deviceand drier system described above. The knots for this system were high at34% indicating that feeding pulp directly is better than forming a wetweb and shredding the web during feed.

Example 8

[0129] Bleached and untreated singulated dried fiber samples wereproduced by pin-fluffing never-dried Southern pine and feeding the pulpby placing it into a foam feed system where water and surfactant areinjected and mixed with the wet pulp providing a flowable mix that canbe fed into the jet drier system. The knots were less than 2% but thefines amount has gone up to almost 20% compared to previous runs.

Example 9

[0130] An unbleached and untreated singulated dried fiber sample wasproduced by running the pulp as obtained from a mill in the dryingsystem described above without the material handling fan between thedrier and the vacuum conveyor. Compared to previous runs, the knotsincreased slightly from 1.8% to 3.5% for the same temperatures.

Example 10

[0131] An unbleached and untreated singulated dried fiber sample wasproduced by running the pulp as obtained from a mill in the dryingsystem described above without the material handling fan between thedrier and the vacuum conveyor. Compared to previous runs, the knotsincreased slightly from 1.3% to 2.6% for the same temperatures. Ableached control sample had a slight increase in knots from 20.4 to21.9%.

Example 11

[0132] A bleached dissolving grade fiber was dried using the dryingsystem described above. The pulp had about 10% knots. The moisture wasless than 2% which is typically too low. Dissolving tests showed thatthe fiber performed about the same as typical commercial grade pulp.

Example 12

[0133] Bleached singulated fiber was produced with the drying systemdescribed above to compare the effect of dewatering process on knots.Screwpressed pulp was compared to centrifuged pulp and centrifugedcontrol wet lap pulp. The results are in Table 12 which shows thatcentrifuging provides a lower amount of knots. TABLE 12 Runs todetermine difference between screw-pressed, centrifuged wet lap, andcentrifuged slush. Two levels of spring pressure were used on the press.Inlet Outlet Sample Spring Average Temp. Temp. Run # PreparationPressure Knots, % Knots Accepts Fines (° C.) (° C.) 32a ScrewpressedHigh 19.3 61.5 19.3 260 180 bleached DF slush 32b Screwpressed High 25.761.1 13.3 280 180 bleached DF slush 32c Screwpressed High 25.6 59.9 14.5280 200 bleached DF slush 32e Screwpressed Low 27.9 57.7 14.3 280 180bleached DF slush 32f Screwpressed Low 22.3 13.3 66.7 20.0 260 180bleached DF slush 33a Control, 20.1 61.7 18.1 260 180 Centrifuged wetlap33b Control, 16.6 65.5 17.9 270 200 Centrifuged wetlap 33c Control, 26.359.1 14.5 280 180 Centrifuged wetlap 33d Control, 21.1 21.3 65.1 13.6280 200 Centrifuged wetlap 34a Centrifuged 20.8 64.0 15.2 260 180 Slush34b Centrifuged 15.6 68.0 16.4 260 200 Slush 34c Centrifuged 14.6 67.917.5 280 180 Slush 34d Centrifuged 17.6 19.2 67.5 13.3 280 200 Slush

Example 13

[0134] Crosslinked bleached singulated fiber was produced with thedrying system described above to determine the ability of the drier torun crosslinked treated pulp. As with other grades of pulp, a low amountof knots is desirable with crosslinked pulp. Two runs were done atdifferent temperatures as shown in Table 13. Polyacrylic acid (PAA XL)was added to the pulp at approximately 5% by weight on pulp. Post curingwas done to complete the reaction. The data shows that the highertemperature in the jet drier lowered sonic knots slightly and loweredwet knots also. Post cure time increased wet knots and may haveincreased sonic knots. The level of sonic knots is considerably higherthan untreated pulp indicating that the polyacrylic acid treatmentincreases knots. Rewetting the crosslinked pulp and drying in an ovenshowed that the pulp did not bond to itself indicating crosslinking ofthe pulp. TABLE 13 Five percent polyacrylic acid treated pulp. Post CureWet Knots Inlet Outlet Sample Time Sonic (% Temp. Temp. Run #Preparation (min) Knots Rejects) Accepts Fines (° C.) (° C.) 35ableached never 0 35.00 0.0 48.33 16.67 286 200 dried w/PAA XL bleachednever 2 32.07 15.35 56.87 11.07 286 200 dried w/PAA XL bleached never3.5 28.93 16.02 58.60 12.47 286 200 dried w/PAA XL bleached never 523.80 18.24 62.13 14.07 286 200 dried w/PAA XL 35b bleached never 028.07 0.26 55.00 16.93 296 210 dried w/PAA XL bleached never 2 24.0014.48 63.00 13.00 296 210 dried w/PAA XL bleached never 3.5 20.40 9.5765.33 14.27 296 210 dried w/PAA XL bleached never 5 24.67 11.28 63.6011.73 296 210 dried w/PAA XL

Example 14

[0135] Clay and fly ash treated bleached singulated fiber was producedwith the drying system described above to determine the effect on sonicknots. The clay and fly ash was added at 0%, 1%, and 10% by weight. Thesamples with 10% mineral have less knots. The fly ash containing fibershad lower knots than the clay containing fibers at the same dosage. Thesamples with 1% mineral do not appear much different than the control.Table 14 provides a summary of the data. TABLE 14 Runs to determineeffect of clay and fly ash on knots. Inlet Outlet Sample Mineral Ac-Temp. Temp. Run # Preparation % Knots cepts Fines (° C.) (° C.) 38Control, 0 19.13 65.80 15.07 270 180 wet lap centrifuged As is 39Control, 1 23.87 63.87 12.27 270 180 wet lap centrifuged With Clay 40Control, 10 10.07 71.27 18.67 270 180 wet lap centrifuged With Clay 41Control, 1 15.93 68.00 16.07 270 180 wet lap centrifuged With Fly Ash 42Control, 10 4.00 69.20 26.80 270 180 wet lap centrifuged With Fly Ash

Example 15

[0136] Singulated fiber was produced using the drying system describedabove from bleached Douglas fir pulp. The pulp was prepared bycentrifuging and then running the pulp through the drier system cold tobreak apart the wet chunks of pulp and then feeding the broken apartpulp through the drier system hot as normal. The purpose is to determinethe efficiency of the drier system to prepare pulp for singulation. Theeffect of outlet temperature on singulation was also tested. Outlettemperature is changed by changing feed rate. At the same outlettemperature, the cold then hot run through the drier reduced knots byhalf. Increasing outlet temperature reduces knots significantly. Theresults are shown in Table 15. TABLE 15 Jet drier runs to determine theeffect of running fiber through the drier system with no heat and thenrunning the same fiber through the system hot. Inlet Outlet ConveyorSonic Temp. Temp. Speed Run # Sample Preparation Knots Accepts Fines (°C.) (° C.) (hz) 46a Control, wet lap 20.13 64.93 14.93 260 170 4.0centrifuged (twice through - cold then hot) 46b Control, wet lap 7.8776.80 15.33 260 197 3.0 centrifuged (twice through - cold then hot) 46cControl, wet lap 8.53 76.73 14.73 260 +200 2.25 centrifuged (twicethrough - cold then hot) 47 Control, wet lap 14.53 70.67 14.80 260 1983.5 centrifuged (once through - hot only)

Example 16

[0137] Singulated fiber was produced using the drying system describedabove from unbleached Douglas fir pulp. The pulp was prepared bycentrifuging it in a batch centrifuge. Sonic knots ranged from 2% to 5%over a several hour period indicating good system stability. The resultsare shown in Table 16, where “run ave” is the mean average of all six(46a-46f) runs. TABLE 16 Jet drier runs to determine system stability.Inlet Outlet Time Sonic Temp. Temp. Run # into run Knots Accepts Fines(° C.) (° C.) 48 Run ave 4.5 84.3 11.2 260 160 48a (1 hour) 5 83 12 260160 48b (2 hour) 4 85 11 260 160 48c (3 hour) 6 84 10 260 160 48d (4hour) 2 87 11 260 160 48e (5 hour) 5 84 11 260 160 48f (6 hour) 5 83 12260 160

Example 17

[0138] Singulated fiber was produced using the drying system describedabove from bleached and unbleached Douglas fir and bleached Southernpine pulp. The pulp was prepared by centrifuging it in a batchcentrifuge. A material handling fan was used to break apart the pulpprior to drying it. Steam heat was used to prepare selected pulps.Different outlet temperatures were also run. The results are shown inTable 17. Steam heating the pulp prior to drying reduced knots. A higheroutlet temperature reduces knots. Unbleached pulp had the lowest amountof knots. TABLE 17 Runs to compare bleached and unbleached Douglas firand bleached Southern pine singulated fibers, as well as steamtreatment. Inlet Outlet Sonic Temp. Temp. Run # Pulp Sample PreparationKappa Knots Accepts Fines (° C.) (° C.) 50a SP Never-dried, bleached, 014.80 69.73 15.47 260 160 slushed, centrifuged, material handling fan50c SP Never-dried, bleached, 0 5.13 73.07 21.80 250 200 slushed,centrifuged, material handling fan, steam heat 50d SP Never-dried,bleached, 0 4.00 75.80 20.20 260 220 slushed, centrifuged, materialhandling fan, steam heat 51a U- Never-dried, 25 2.60 85.67 11.73 260 160DF unbleached, centrifuged, material handling fan 52 B- Control, wet lap0 16.20 70.73 13.07 260 160 DF centrifuged 52a B- Control, wet lap, 013.13 75.67 11.20 230 180 DF centrifuged, steam heat 52b B- Control, wetlap, 0 8.40 75.33 16.27 250 200 DF centrifuged, steam heat 52c B-Control, wet lap, 0 10.53 77.27 12.20 260 220 DF centrifuged, steam heat

Example 18

[0139] Singulated fiber was produced using the drying system describedabove from bleached Douglas fir and bleached Southern pine pulp. Thepulp was prepared by centrifuging it in a batch centrifuge. A materialhandling fan was used to break apart the pulp prior to drying it.Passing the pulp through the jet drier system with the heat off was doneon selected samples. The results are shown in Table 18. Sonic knotsranged from 1.87 to 10.07. Running the pulp through the system with theheat off prior to drying the pulp reduced knots. TABLE 18 BleachedDouglas fir and Southern pine with no treatment but with selecteddefiberization. Inlet Outlet Sonic Temp. Temp. Run # Pulp SamplePreparation Knots Accepts Fines (° C.) (° C.) Null 53a B-SP Never dried,bleached, 1.87 79.93 18.20 250 185 −3.5-4.0 slushed, centrifuged,material handling fan Run twice - cold/hot 53a2 B-SP Never-dried,bleached, 10.07 72.60 17.3 250 177 −3.5 slushed, centrifuged, materialhandling fan Hot only 53a2 sub sample - 1 9.87 75.33 14.8 53a2 subsample - 2 6.87 74.87 18.2 53a2 sub sample - 3 9.33 73.47 17.2 53b B-SPNever-dried, bleached, 9.40 72.40 18.2 250 171 −3.5 slushed,centrifuged, material handling fan Hot only 54a B-DF Control, wet lap3.00 82.20 14.80 250 −5 bleached, centrifuged, material handling fan Runtwice - cold/hot 54a2 B-DF Control, wet lap, 5.87 80.73 13.40 250 177−3.5-4.0 bleached, centrifuged, material handling fan Run twice -cold/hot 54b B-DF Control, wet lap, 980 77.67 12.53 250 171 −3.5bleached, centrifuged, material handling fan Hot only

Example 19

[0140] Singulated fiber was produced using the drying system describedabove from bleached Douglas fir treated with 0.1% sodium dodecylsulfate. The pulp was prepared by centrifuging it in a batch centrifugeafter treatment. Passing the pulp through the jet drier system with theheat off was done on the samples. The results are shown in Table 19.Sonic knots ranged from 0.73 to 2.27% indicating that surfactanttreatment significantly reduces sonic knots. TABLE 19 Runs on bleachedDouglas fir pulp treated with 0.1% sodium dodecyl sulfate. Inlet OutletAmount Sonic Temp. Temp. Run # Sample Preparation (kg) Knots AcceptsFines (° C.) (° C.) 55 Control, wet lap 3 1.07 84.40 14.53 250 180bleached, slushed in separate 0.73 83.80 15.47 0.1% solution of SDS,bags for 0.73 84.00 15.27 centrifuged only testing Run twice - cold thenhot 56 Control, wet lap 3 1.33 85.00 13.67 240 170 bleached, slushed,separate 2.27 83.93 13.80 centrifuged, material bags for 0.87 85.0714.07 handling fan testing Run twice —cold then hot 57 Control, wet lap3 1.00 83.13 15.87 240 170 bleached, slushed in separate 1.00 83.6715.33 0.1% solution of SDS, bags for 1.00 83.93 15.07 centrifuged onlytesting Run twice - cold then hot

Example 20

[0141] Singulated fiber was produced using the drying system describedabove from bleached Southern pine (B-SP) with and without latextreatment and from unbleached and bleached Douglas fir (U-DF and B-DF,respectively) pulp. The bleached Southern pine pulp was prepared bycentrifuging slushed pulp, running it through a material handling fan,and then running it through the jet drier with the heat off prior todrying it. The unbleached Douglas fir was only centrifuged afterslushing. The latex treated bleached Southern pine pulps were preparedby passing the pulps through the jet drier system with the heat offafter treatment and centrifuging. The bleached Douglas fir control pulpwas only centrifuged after slushing. The results are shown in Table 20.Sonic knots are low on the bleached Southern pine indicating themechanical treatments reduce knots. The unbleached Douglas fir pulp hadthe lowest knots indicating that it fiberizes well in this system. Thelatex treated pulps also had low knots showing that the latex may reduceknots or may not affect their production. The control bleached Douglasfir had low knots indicating an improvement in the drier system. Thelatex treated pulps were hydrophobic.

[0142] Table 20: Singulated Southern pine and Douglas fir pulps runthrough the drier with no heat. Inlet Outlet Sonic Temp. Temp. Run #Pulp Sample Preparation Knots Accepts Fines (° C.) (° C.) 58 B-SPBleached, never-dried, 1.07 81.07 17.87 240 167-170 slushed,centrifuged, 1.67 79.40 18.93 material handling fan 3.67 78.53 17.80 Runtwice - cold then hot 59 U-DF centrifuged only 0.80 85.73 13.47 240167-170 Run hot only 60 B-SP Latex #1 1.27 88.20 10.53 240 160-165 Runtwice - cold and hot 61 B-SP Latex #2 1.60 84.00 14.40 240 160-165 Runtwice - cold and hot 62 B-SP Latex #3 1.33 84.60 14.07 240 160-165 Runtwice - cold and hot 63 B-SP Latex #4 1.07 84.93 14.00 240 160-165 Runtwice - cold and hot 64 B-DF Control, wet lap 2.20 83.67 14.13 240167-170 bleached, slushed, centrifuged only

Example 21

[0143] Singulated fiber was produced using the drying system describedabove from bleached Douglas fir pulp. The pulps were prepared bycentrifuging only, centrifuging and running through a material handlingfan, centrifuging and running through the drier with the heat off beforedrying or adding chemical surfactant prior to centrifuging. The resultsare in Table 21. Pulp that had been centrifuged or centrifuged and runin the material handling fan were about equal in sonic knots at 15%.Running centrifuged pulp through the system with no heat reduced knotsto about 10%. The surfactant treatment reduced knots to about 3%. Theseresults were duplicated in follow-up runs. Conveyor speed was 7 ft/min,null was −3.5 to −4 inches water. TABLE 21 Singulated bleached Douglasfir pulp comparing mechanical fiberization pulp preparation to Berol587k chemical surfactant. Inlet Outlet Sonic Temp. Temp. Feed Run #Sample Preparation Knots Accepts Fines (° C.) (° C.) Rate 65 Control,wet lap bleached, 15.33 71.47 13.20 260 180 150 slushed, centrifuged,material handling fan Hot only 66 Control, wet lap bleached, 9.93 76.1313.93 260 180 150 slushed, centrifuged only, Cold then Hot 67 Control,wet lap bleached, 2.88 85.80 11.32 260 180 150 slushed, centrifuged with1% surfactant Hot only 68 Control, wet lap bleached, 15.62 72.03 12.35260 180 150 slushed, centrifuged only, Hot only

Example 22

[0144] Singulated fiber was produced using the drying system describedabove from bleached Douglas fir pulp and Southern pine pulp with andwithout polyacrylic acid crosslinker, surfactant, and clay treatments.The pulps were prepared by centrifuging only or centrifuging and runningthrough a material handling fan (MHF) prior to drying. The results arein Table 22. The Douglas fir control had 9% knots. The Southern pinewith surfactant had 2% knots confirming the benefit of surfactant. Thepolyacrylic acid only treatment increased knots to 15%. Addingsurfactant or clay to the polyacrylic acid treated pulp reduced knotsbelow 2% demonstrating the benefit of surfactant and clay to reduceknots. The inlet temperature was 240° C. and outlet temperature was 165°C. Null was −3.5 inches of water and conveyor speed was 6.0 ft/min.TABLE 22 Singulated bleached Douglas fir control and Southern pine pulpwith and without polyacrylic acid, surfactant, and clay treatments. ODFeed Rate Run # Pulp Sample Preparation Clay Knots Accepts Fines (g/min)75 B-DF Control, wet lap centrifuged 0 9.00 79.47 11.53 71.02 Hot only76 B-SP Bleached, never-dried, 0 2.07 84.93 13.00 83.15 slushed,centrifuged, MHF, with 1% surfactant 77 B-SP Bleached, never-dried, 014.87 65.80 19.33 92.63 slushed, centrifuged, MHF, w/20% PAA on fiber 78B-SP Bleached, never-dried, 0 1.60 85.40 13.00 89.71 slushed,centrifuged, MHF, w/20% PAA on fiber and with 1% surfactant 79 B-SPBleached, never-dried, 10 1.20 77.80 21.00 88.07 slushed, centrifuged,MHF, w/20% PAA on fiber 80 B-SP Bleached, never-dried, 20 1.80 76.6721.53 86.91 slushed, centrifuged, MHF, w/20% PAA on fiber

Example 23

[0145] Singulated fiber was produced using the drying system describedabove from two different bleached Douglas fir pulps with selectedamounts of Berol 587k surfactant on one of the pulps. One batch of pulpwas treated with soluble iron. The pulps were prepared by centrifugingonly. The results are in Table 23. The surfactant works best at the 1%dosage level. The iron reduced knots significantly but also increasedfines to a high level. Feed rate may have had an influence on thesurfactant results. Higher feed rates appear to increase knots. Theinlet temperature was 240° C. and outlet was 160 C. The conveyor speedwas 6 ft/min and null was −3.5 inches water. TABLE 23 Run to determineminimum amount of surfactant needed to reduce knot content below 2%using the bleached KKT from Kamloops. OD Feed % Sonic Rate Run # PulpSample Preparation Surfactant Knots Accepts Fines (g/min) 85 B- Control,slushed, 0 4.20 82.07 13.73 75.80 DF#2 centrifuged only Hot only 86 B-Slushed, centrifuged, 0.1 4.13 81.00 14.87 108.32 DF#2 w/surfactant,centrifuged Hot only 87 B- Slushed, centrifuged, 0.5 3.73 84.33 11.9390.51 DF#2 w/surfactant, centrifuged Hot only 88 B- Slushed,centrifuged, 1.0 2.00 86.27 11.73 73.25 DF#2 w/surfactant, centrifugedHot only 89 B-DF Wet lap centrifuged 0 1.93 65.27 32.80 71.90 (bleached)with 0.05% Fe3+ 90 B-DF Control, wet lap 0 5.00 80.67 14.33 71.56bleached, slushed, centrifuged - end of run sample Hot only

Example 24

[0146] Singulated fiber was produced using the drying system describedabove from bleached Douglas fir pulp that had been dewatered using ascrewpress. The results are in Table 24. The amount of knots issufficiently low compared to previous runs to show that screwpressdewatering is an acceptable option to remove excess water prior todrying pulp with the jet drier system. TABLE 24 Singulated bleachedDouglas fir prepared from pulp dewatered through a screwpress. InletOutlet Sonic Temp. Temp. Run # Sample Preparation Knots Accepts Fines (°C.) (° C.) Null 91 Control, wet lap bleached, 3.20 85.87 10.93 240189-190 −3.5 slushed, centrifuged, material handling fan Cold then Hot92 Never-dried, Screw pressed 3.87 82.33 13.80 240 169-171 −3.5 to (HC >30), material −4.0 handling fan Hot only

Examples 25-29

[0147] The pulps used in Examples 25 through 29 were all never-driedpulps of approximately 10% consistency shipped directly from the pulpmill in plastic-lined fiber drums. The procedure for preparing andtreating the pulp with crosslinking chemicals included the steps of: (a)centrifuging the never-dried pulp to a uniform consistency ofapproximately 34%, (b) treating the pulp with crosslinking chemicals ina large Hobart mixer at a consistency of approximately 5%, (c)centrifuging the treated pulp to a consistency of approximately 36%(higher now due to retained chemical solids), and (d) delumping thecentrifuged, treated pulp in the Hobart mixer to achieve uniformparticle size.

[0148] In all the examples, the jet drier system as described above wasused to singulate and dry the fibers. After passing through the jetdrier, the dry singulated fibers were first collected and then cured inan oven. Crosslinking was only partially effected in the jet drier.Crosslinking was completed by curing the treated fiber for severalminutes at an elevated temperature in a curing oven.

[0149] Testing of crosslinked fiber often includes sonic fractionationto determine the percentage of knots, accepts, and fines as describedabove.

[0150] The primary attributes of crosslinked fiber are high bulk andretention of bulk when wet. The FAQ test is used for measuring both wetand dry bulks. “Resaturation bulk at 0.6 kPa” is usually the test resultthat is of most interest and is the value used when FAQ results arelisted in the examples. FAQ's for commercially available crosslinkedfiber typically range from 13.5 to 19.0 cc/g with higher values beingpreferred.

Example 25

[0151] In this example, bleached, never-dried, Southern Pine was used.The crosslinker was DMDHEU. The post-jet drier cure time was about 5minutes at 170° C. TABLE 25 Singulated Pulp Crosslinked With DMDHEUManifold Outlet Crosslink Temp. Temp. Null Press. Knots Accepts FinesFAQ Run # (% ODF) (C.) (C.) (in of H₂O) (%) (%) (%) (cc/g) 91 2.0 220135 −4.5 4.0 79.3 16.7 13.6 92 3.0 220 132 −4.5 4.3 79.0 16.7 13.6 934.0 220 135 −4.5 4.1 78.9 17.0 13.6 94 2.0 200 115 −4.5 4.3 80.2 15.513.7 95 3.0 200 112 −4.5 5.0 79.7 15.3 13.6 96 4.0 200 113 −4.5 4.8 77.617.6 13.8

Example 26

[0152] In this example, bleached, never-dried, Southern Pine pulp wasused. The linker was citric acid. The post-drier cure time was about 5minutes at 170° C. TABLE 26 Singulated Pulp Crosslinked With Citric AcidCross- Mani- Null link fold Outlet Press. Run (% Temp. Temp. (in ofKnots Accepts Fines FAQ # ODF) (C.) (C.) H₂O) (%) (%) (%) (cc/g) 97 5.7200 110 −4.5 4.1 79.9 16.0 15.1 98 5.7 200 112 −4.0 4.7 81.2 14.1 14.999 5.7 200 113 −4.0 3.7 82.6 13.7 15.1 100 11.5 200 113 −4.5 5.2 81.513.3 16.3 101 11.5 200 113 −4.5 3.9 83.6 12.5 16.2 102 11.5 200 116 −4.03.6 82.9 13.5 16.0

Example 27

[0153] In this example, bleached, never-dried, Southern Pine was used.The crosslinker was Malic acid. The post-drier cure time was about 20minutes at 185° C. TABLE 27 Singulated Pulp Crosslinked With Malic AcidCross- Mani- Null link fold Outlet Press. Run (% Temp. Temp. (in ofKnots Accepts Fines FAQ # ODF) (C.) (C.) H₂O) (%) (%) (%) (cc/g) 10310.0 180 106 −2.0 5.5 77.9 16.6 16.1 104 10.0 180 108 −4.5 3.7 79.4 16.916.3 105 10.0 200 127 −2.0 4.2 80.9 14.9 16.1 106 10.0 200 123 −4.5 3.782.4 13.9 16.3 107 10.0 220 130 −1.5 4.0 80.9 15.1 16.3 108 10.0 220 135−4.5 3.9 81.0 15.1 16.3 109 10.0 220 129 −6.0 3.9 82.9 13.2 16.4

Example 28

[0154] In this example, unbleached, never-dried, Southern Pine wasnoted. The crosslinker was Malic acid. The post-drier cure time wasabout 4 minutes at 200° C. TABLE 28 Singulated Pulp Crosslinked WithMalic Acid Cross- Mani- Null link fold Outlet Press. Run (% Temp. Temp.(in of Knots Accepts Fines FAQ # ODF) (C.) (C.) H₂O) (%) (%) (%) (cc/g)110 10.0 185 106 −4.5 0.3 87.3 12.4 17.6 111 10.0 185 100 −6.5 0.5 88.411.1 18.0 112 10.0 200 116 −4.5 0.7 87.8 11.5 17.9 113 10.0 200 110 −6.00.3 87.7 12.0 18.1 114 10.0 185 124 −5.5 0.7 86.2 13.1 17.8

Example 29

[0155] In this example, unbleached, never-dried, Southern Pine was used.The crosslinker was Malic acid. The post-drier cure time was 4 minutesat 200° C. TABLE 29 Singulated Pulp Crosslinked With Malic Acid Cross-Mani- Null link fold Outlet Press Run (% Temp. Temp. (in of KnotsAccepts Fines FAQ # ODF) (C.) (C.) H₂O) (%) (%) (%) (cc/g) 115 2.0 200118 −5.5 2.0 84.1 13.9 15.9 116 4.0 200 118 −5.5 2.2 84.4 13.4 17.1 1176.0 200 119 −5.0 2.0 83.0 15.0 17.3 118 8.0 200 118 −5.0 1.3 83.8 14.917.9

[0156] While the preferred embodiment of the invention has beenillustrated and described, it will be appreciated that various changescan be made therein without departing from the spirit and scope of theinvention.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:
 1. A process for producingcrosslinked, singulated pulp fibers comprising: introducing a wet pulpand air into a jet drier; treating said wet pulp with a crosslinker;thereafter drying said pulp in said jet drier to form singulated pulpfibers; and removing said pulp from said jet drier and separating saidpulp fibers from said air.
 2. The process of claim 1, wherein saidcrosslinker is selected from the group consisting of polyacrylic acid,glyoxal, malic acid, and tartaric acid.
 3. The process of claim 1,wherein said treatment substance is mixed with said wet pulp beforeintroducing said wet pulp into said drier.
 4. The process of claim 1,wherein said wet pulp is at least partially dewatered prior tointroducing said pulp into said drier.
 5. The process of claim 1,wherein said wet pulp is further treated with a treatment substance toreduce the knot content of said pulp fibers, selected from the groupconsisting of a surfactant and a mineral particulate.
 6. The process ofclaim 5, wherein said treatment substance is a mineral particulate. 7.The process of claim 5, wherein said treatment substance is asurfactant.
 8. The process of claim 1, wherein said wet pulp is furthertreated with a substance selected from the group consisting of ahydrophobic material, a superplasticizer, a foam, surfactant caused toand a water reducing agent.
 9. The process of claim 1, wherein the knotcount of said pulp fibers is less than 15%.
 10. The process of claim 9,wherein the knot count of said pulp fibers is less than 10%.
 11. Theprocess of claim 9, wherein the knot count of said pulp fibers is lessthan 5%.
 12. The process of claim 9, wherein the knot count of saidfibers is less than 2%.
 13. The process of claim 5, wherein said fibershave a knot count less than 15%.
 14. The process of claim 13, whereinsaid fibers have a knot count less than 10%.
 15. The process of claim13, wherein said fibers have a knot count less than 5%.
 16. The processof claim 13, wherein said fibers have a knot count less than 2%.
 17. Theprocess of claim 1, wherein the knots count is less than or equal to 5%,the accepts are greater than or equal to 80%, and the fines are lessthan or equal to 15%.
 18. The process of claim 1, wherein the knotscount is less than or equal to 5%, the accepts are greater than or equalto 80%, and the fines are less than or equal to 13%.
 19. The process ofclaim 1, wherein the knots count is less than or equal to 5%, theaccepts are greater than or equal to 85%, and the fines are less than orequal to 15%.
 20. The process of claim 1, wherein the knots count isless than or equal to 2%, the accepts are greater than or equal to 80%,and the fines are less than or equal to 15%.
 21. The process of claim 6,wherein the knots are less than or equal to 2%, the accepts are greaterthan or equal to 77%, and the fines are less than or equal to 21%. 22.The process of claim 7, wherein the knots are less than or equal to 5%,the accepts are greater than or equal to 80%, and the fines are lessthan or equal to 15%.
 23. The process of claim 7, wherein the knotscount is less than or equal to 5%, the accepts are greater than or equalto 80%, and the fines are less than or equal to 13%.
 24. The process ofclaim 7, wherein the knots count is less than or equal to 5%, theaccepts are greater than or equal to 85%, and the fines are less than orequal to 15%.
 25. The process of claim 7, wherein the knots count isless than or equal to 2%, the accepts are greater than or equal to 80%,and the fines are less than or equal to 15%.
 26. The process of claim 1,wherein said supply pulp has a consistency of from 0.01% to 10% beforeintroduction into said jet drier.
 27. The process of claim 26, whereinsaid supply pulp has a consistency of from 3% to 10% before introductioninto said drier.
 28. The process of claim 1, wherein said singulatedpulp is dried to a moisture content of less than 2 percent to 10 percentby weight.
 29. A process for producing singulated pulp fiberscomprising: introducing wet pulp containing a crosslinker and air into ajet drier through a rotary airlock, said rotary airlock having vanes anda housing, the end of said vanes being spaced from said housing by adistance sufficient to prevent wet fibers from clogging said airlock.30. The process of claim 29, wherein said gap between said vane end andsaid housing is in the range of 0.010 to 0.050 inches.
 31. The processof claim 29, wherein said vanes shear fiber clumps as they enter saidhousing to prevent clogging said airlock.
 32. A process for producingsingulated pulp fibers comprising: introducing a wet pulp containing acrosslinker and air into a jet drier, drying said wet pulp in said jetdrier to form crosslinked, singulated pulp fibers; withdrawing saidfibers from said jet drier in an air stream at a velocity sufficient toprevent said fibers from knotting; and separating said pulp fibers fromsaid air stream.
 33. The process of claim 32, wherein said pulp fibersare withdrawn from said drier through a conduit, said conduit beingsized and said air stream being maintained at a velocity sufficient tomaintain fibers suspended in said air stream in said conduit.
 34. Theprocess of claim 32, further comprising curing said pulp fibers aftersaid pulp fibers are separated from said air stream.
 35. The process ofclaim 32, further comprising flash drying said pulp fibers after saidpulp fibers are separated from said airstream; and curing the flashdried pulp fibers.
 36. A process for producing singulated pulp fiberscomprising: introducing wet pulp containing a crosslinker and air into ajet drier; drying said wet pulp in said jet drier to form singulatedpulp fibers; and withdrawing said pulp fibers from an outlet from saidjet drier under a partial vacuum.
 37. The process of claim 36, whereinsaid vacuum is applied to a plenum, the process further comprising:positioning a head box at the outlet; positioning a movable screenbetween said plenum and said head box on which said pulp fibers anddeposited, said head box and said plenum being in sealing contact withsaid screen; and moving said screen past said head box to remove pulpfibers from said head box.
 38. The process of claim 37, wherein saidfibers emerge from said head box at an outlet side as said screen ismoved, the process further comprising: positioning a second plenum undersaid screen adjacent said outlet side; and drawing a partial vacuum insaid second plenum to hold said fibers on said screen as they emergefrom said head box.
 39. Singulated pulp fibers produced by the processas in claim 1.